How important is the shape of a knife blade?

The shape of a knife blade, to a large extent determines the absolute use of the knife. Humans have made knives for millions of years. These are our most evolved and revered of tools. We've had millennia to define, refine, and perfect the knife blade, and yet there are thousands of designs. Why? (See my own 360+ designs here) Because, as simple as it would seem, a tiny variation in length, curvature, profile, thickness, and grind changes the knife completely. It's funny how just .03" of difference will make the knife blade look entirely distinctive. People notice this. I believe that man has made the knife for so long that it's possible that the pattern is somehow recognized on a genetic level. People relate to knives that way. Handles notwithstanding, I've seen clients stare and compare and tune and modify the pattern in the slightest way to reach that perfect shape that they think is just right. Where does that come from? Have they really used knives that much to be able to distinguish miniscule differences in what is right for them? There is something deeper here, something at the very core of the human psyche. That's another discussion for my book.

In a basic way, knife and blade use can be classified by shape. A long sweeping, curving blade is usually called skinning, or fleshing. A heavy, large aggressive-looking straight blade is usually called combat or tactical. I try to stay away from the term "fighting knife," as this is a negative and unrealistic designation for a modern knives.

Many knives are classified depending on the physical attributes of their profile, such as drop point, clip point, trailing point, and swage.

Here are some classifications of knives based on description of both use and blade shape:

Other blade shapes not shown by example are curved, razor, wharncliffe, square, kris, dirk, jambiya, stiletto, spey, smatchet, hawksbill, katar, and chakmak. There are a tremendous amount of variations in knife blades, and some of the blade styles incorporate the geometry of several different defined shapes. As the knife blade evolves, some new styles will undoubtedly be named, and the clear definitions of blade styles and shapes may be blurred or even discarded. For example, it would be ridiculous to describe a knife as a modified spear point with trailing point and tanto attributes with a recurve body and hollow ground swage... but I've done that! Ultimately, a photograph or illustration is necessary.

Knife Use Classifications

Knife blade shapes can also be classified by their use. This is a more casual affair, as most blade shapes can be used for a variety of cutting, slicing, or (in the case of combat knives) stabbing requirements. Some of the direct use classifications are: butchering, hunting, kitchen, chef's, caping, skinning, utility, combat, defense, CQC (Close Quarters Combat),assault, CQB (Close Quarters Battle), sport, camp, survival, CSAR (Combat Search and Rescue), fantasy, sculptural, art, woodcraft, fillet, personal, bird, trout, ceremonial, carving, collector's, investment, museum, fine art, and simply working knives. There are many more: specialized descriptions, specialized uses, individual, dedicated knives, and knives that may cover several or many of the classifications listed.

Aren't all knives about the same?

If all knives were the same, we'd only have one design, and you would see it everywhere. Instead, you'll see thousands of knife designs in the modern world. I make over 360 different designs myself. Imagine all the varied designs created throughout history, and you'll soon realize the tremendous variety of knives. There simply is no other tool or device that has so many variations and knives are astounding forms.

The person asking this might be wondering about comparisons between a handmade custom knife and a factory knife. Though this topic comes up infrequently, it is important to educate those who may try to form a realistic comparison of these two very different origins and fabrications of the same tool, art, or piece. This discussion is prevalent enough to deserve its own dedicated page on my site: Factory Knives vs. Handmade Custom Knives. Simply put:

Visit the page to find out why.

What about factory or manufactured knives?

A factory or manufactured knife can not compare to a handmade custom knife. Just because they share the same form, a blade and handle and sheath, it does not mean that they are in the same realm. Find out the difference between a knife that sells for a hundred bucks, and one that starts at ten times that much on this special page dedicated to the topic.

In the specific and detailed subject of blades, the most important thing to remember is that factories need something to sell, something made cheaply but sold for as much as their market will bear. So for the blades, they often offer special steels that they claim are superior to the recognized AISI steels. They also are very careful not to reveal the steel alloy components or actual properties like tensile strengths, heat treating process, corrosion resistance, wear resistance and other factors and instead, claim things like, "testing has determined that our steel has superior performance, wear, and corrosion resistance than 440C, ATS-34, etc."

Don't be fooled by this hype. Any of these so-called tests are entirely subjective, and can be easily directed toward the intended result, which (shock) is always in favor of their special steel. Without revealing the exact components of the steel, there is no scientific way to test it. This is because testing, real scientific metallurgy must have as its basis the knowledge of the steel alloy components and method of manufacture as well as all the properties, mechanical and exposure, that the steel has or will be exposed to.

Let's make a simple, realistic comparison. A skyscraper is under construction. The head engineer of the ironworks company has read on the "Mystical Bolt Company" website that bolts are available, that they are a special and secret alloy, but they perform better than known, recognized, and accepted industry standards. No technical specifications exist on the bolt maker's site: no alloy content, no process of manufacture, no tensile strength, impact strength, yield, elongation, area reduction at specific hardnesses and tempers depending on specific and varied heat treating and manufacturing processes is offered. On the bolt maker's site are just vague generalities about performance. Not one engineer on earth would sign off on the purchase of our fastener for the integrity of its properties and application on the project without knowing even what the material is.

Yet in the world of knife manufacture and sales, it's almost expected that the factory will supply some special, proprietary, or unique and mysterious steel that outperforms all other known types. Really? It seems each factory follows the same advertising formula, claiming a special designation, comparing in generalities the qualities to known types, claiming superiority and thus value, sometimes adding performance anecdotes like chopping pine two-by-fours, shoving the blade in a car door, or bending, leaving submersed in water, or other ways of brutalizing a piece of overly thick steel. Then, to top it off, organizations and interests claim that certain knives must be certified (by them) for the honor of being tested in this anecdotal, subjective, and extremely unscientific way. Usually, this requires the donation of a knife or knives for this honor!

This is all advertising hyperbole, so that you will think that the inexpensive factory knife is somehow superior to other inexpensive factory knives. All the while, the knife lacks balance, has an unfinished blade, is poorly fitted, has cheap or non-durable handle materials, poorly made or non-existent fittings, no contouring or radiused forms, horrible fit, weak mechanical construction, lack of bedding, poor design, simply awful sheaths or accessories (or none at all!), and no service, except for one or two companies who will sharpen your knife for a fistful of dollar bills. These knives will never be worth more than they are when they are purchased, never have any long-term value, are not custom, are not well made, and most individual knife makers create a product that is many times and many ways superior to factory or manufactured knives. But since the factory's business is built on volume, not quality, this doesn't matter.

Thankfully, the internet is changing all that. This very medium has been the source of real, valid information in not only the field of knives, but it all fields of interest and knowledge known to mankind. You are very lucky that you are in a country that allows the technology and access that allows you to read this very sentence, and that you are living in an exciting time of the growth of knowledge and ultimately truth that the Internet can bring. You've just got to wade through the hype to get to it!

In my book, I'll go through just how significant and powerful this opportunity called the internet is, and how it's changing the way people do business, access products, learn, grow, and excel, deepen, and enrich their lives and the lives of their families with this tool of knowledge. I'll also detail how the vague, indiscriminate advertising hype that was started in print media that was limited to "pay by the letter" generalities has to face the reality of fact-based transparency. The practices of using power words and catch phrases is falling to the detailed and specific facts of product properties. But the factories don't get it yet, and maybe, because their products are cheap and made en masse, they never will.

My point about steel types, blades, and hand knives is simple. There are known and listed steel types with known and listed mechanical and exposure properties. They are known and listed by real entities like the American Iron and Steel Institute (AISI), the Society for Automotive Engineers (SAE), and the American Society for Testing and Materials (ATSM). They are listed because they are established materials in industry, the military, and even the medical equipment fields. If there were a really special steel, something so great that it lived up to the advertising hype posted on these factory knife sites, wouldn't you see all other steels tossed aside and become obsolete while the new steel took over the military industrial commerce? Of course you would. Established and well known steel types exist for a reason, and each reason varies in our world. There is no steel that dominates in all realms. A super hard steel may be brittle, a wear resistant steel may easily corrode. A lightweight material may be soft, a high wear resistance material may not be able to be finished or sharpened by hand. Every material has its pros and cons and I list those on this very page. You won't find factories listing any cons on any of their products, yet they do not supply a knife that is good enough to choke out the competition. Please think about that.

What are tool steels and why are they used?

Yes, Virginia, there are specifically classified tool steels, and they are specifically used to make tools for the working and forming of woods, plastics, and other metals. This is the definition of tool steel (from the Machinist's Guide). They have to withstand high loads, abrasive contact, elevated temperatures, shock, stress, and adverse conditions without suffering major damage, edge dulling, or metallurgical changes.

Not all tools are made of tool steels! Tools used to cut wood, make hand saws for woods, ordinary hand tools, hammers, chisels, and files are often made from standard steels in the AISI/SAE/ATSM categories. The tool steel category is a separate group, and must absolutely be heat treated, hardened, and tempered. There are a large number of tool steels, with specific and controlled alloy compositions. Industry has created a specific classification systems for these tool steels in seven categories. They are:

• Water Hardening Tool Steels
• Mold Steels
• Shock Resisting Tool Steels
• Cold Work Tool Steels
• Hot Work Tool Steels
• High Speed Tool Steels
• Special Purpose Tool Steels

These categories are only the beginning of specific identification of tool steels and uses. Each category has sub-categories, and many steels cross over to a variety of uses. For instance, O-1 and D2, two of my favorite tool steels, are in the category of Cold Work Tool Steels. They are hardened by quenching in either oil or air, so the hardening method is not always the designator of the tool steel category. You might hear someone group metals as "oil-hardening" or "air hardening." These are NOT individual recognized categories, the specific seven categories are listed above. Hey, I didn't make this system up, it's the industry standard!

Stainless steels have a different classification system. It's unusual, because in AISI/SAE/ATSM, in order to classify as a stainless steel, they must contain at least 10% chromium. But the practice in the steel industry has been to classify steels with as little as 4% chromium as stainless steels! Some steels, like D2, for instance, contain 12% chromium, but are actually in the category of Cold Work Tool Steels, not specifically limited to the stainless steel category. Stainless steels are one of three types:

• Austenitic grades
• Ferritic grades
• Martensitic grades

In industrial standards (which we as metal smiths refer to) the term stainless steel refers to high-alloy steels which have superior corrosion resistance to conventional and carbon steels because they contain relatively large amounts of chromium. In a broad sense, standard stainless steels fall into one of the three categories: (austenitic, ferritic, and martensitic).

Austenitic grades of stainless steels are non-magnetic in the annealed condition, but may become slightly magnetic after cold working. They can only be hardened by cold working, and do not harden in heat treat. A good example of austenitic stainless steel is 304 or 18-8, used for many stainless fasteners. I prefer 304 SS for many of my bolsters and fittings, as it is highly corrosion resistant, tough, and requires no care. Please remember that the material I use in my bolsters is the same material as most stainless steel bolts, screws, and fasteners, built for strength, durability, and longevity!

Ferritic grades are always magnetic and contain chromium, but no nickel. They can be somewhat hardened by cold working, but not by heat treatment. They have moderate mechanical properties, high decorative appeal, and a narrower range of corrosion resistance. Some of the ferritic grades contain alloys that help prevent hardening. A good example is 405 stainless, which is often used because it can be easily welded and used in the as-welded condition, and is soft and ductile.

Martensitic grades of stainless steel are magnetic and can be hardened by heat treating, quenching, and tempering. They contain chromium and with several exceptions, no nickel. Many of the martensitic grades contain increased carbon content, in the tool steel range, and are hardenable to the highest levels of all the stainless steels. Though they are not resistive to extremely corrosive atmospheres, they have excellent service in most atmospheres and exposures. 440C, for instance, is used to make corrosion resistant ball bearings, high-wear valve parts, molds and dies, and of course, fine knife blades!

You'll see me referring to these grades in my description of knife steels and fittings I use in my own work.

Now if this is not confusing enough, here are the specific designations of steels (which are separate from the classification or the category). This is the standard, held by AISI (the American Iron and Steel Institute) and SAE (the Society of Automotive Engineers), and is the coordinated industry standard of steel designation:

• Carbon Steels
• Manganese Steels
• Nickel Steels
• Nickel-Chromium Steels
• Molybdenum Steels
• Chromium-Molybdenum Steels
• Nickel-Chromium-Molybdenum Steels
• Nickel-Molybdenum Steels
• Chromium Steels
• Chromium-Vanadium Steels
• Tungsten-Chromium Steels
• Silicon-Manganese Steels
• High Strength-Low Alloy Steels
• Chromium-Manganese-Nickel Steels
• Chromium-Nickel Steels

Okay, I hope that clears it up for you! Want to know more? Pick up a copy of the hundred dollar book, the Machinery's Handbook© and the Study Guide at a bookstore or on line. There's more info in there on steel and other materials than you'll probably ever need!

What about the latest new miracle steel I've heard so much about?

Whether is CPMS30V, 440CPV, BG42, CPM(T)440V, AUS10 CGRF80LG, or BR5-49: you're convinced. One of these "new" steels is the answer to your knife dreams. The steel will hold a razor's edge forever, can be hammered through a steel anvil, bend 45° without breaking, never rust, weigh only a feather, pry diamonds out of raw stone, then shave your facial hair, cut the umbilical cord on your new baby, send waves of terror through aggressors at the mere sight of it, send waves of awe through fellow collectors at the mere thought of it, and preserve freedom for all mankind. Really?

Hopefully, you've read about the factory practice of special steel designations in the topic above, and more information on these practices are detailed on my Handmade Custom Knives vs. Factory Knives page.

I get these questions all the time. Is this latest craze or a gimmick, or is there a real new miracle tool steel? If there were a miracle steel, don't you think that it would sweep the country, be used on the latest high quality military grade and medical machines? Wouldn't it be used to cut other metals on machine tools like lathes, mills, boring machines, planers, drills and other machines? Why, of course it would. So what is all the hoopla about? Pop steels, that's what. In the 1980s it was 154CM, in the early 1990s it was ceramics, in the late 1990s it was BG42, and lately it's been CPMS30V. Look, they are all good steels (except ceramics, which are not steel at all) and they all can make and still do make a fine knife. I've used them and will continue to do so, but they have limitations as do all steels. So why are these pop steel trends so prevalent?

Factories, knife makers, dealers, importers, and salesmen always need something new. That is because they must continually sell the hyperbole, to generate interest in their product. Usually, this is because of poor overall product design. In knives, the fit and finish and balance and accessories are all labor-intensive high skill areas of production, and the fine hands-on workmanship required to make a fine finish, fit, balance, and accessories often does not happen. Factories and low quality makers then rely upon gimmicks, tricks, hype, and envy to sell their product. So, every couple years, a new steel hits the market and all the guys are talking about it. It's on the forums, in the magazines, and in discussions at shows. It's the future of knife making, lots of sales are made based on it, and then it just fades away as another gimmick steel name starts dripping off the drooling tongues of dealers, suppliers, factories, collectors, and makers. Read more about this and other knife truths at my Factory Knives vs. Custom Handmade Knives page. It does not mean that these popular steels are not worth investing in, they may well be. But will they replace all tool steels in knife blades? Of course not, because every steel has its advantages and disadvantages.

Though there are very good tool steels, there is no super steel. You can read more details about this on my FAQ page at the question: "Is there an ultimate blade?" My military, police, professional collectors know that with most production knives, the hype is thicker than fertilizer at a feed lot. Yes, there are some very good knives out there, made of fine steels. I even use many of the steels I've identified above because they are good steels. But more attention should be paid to design, fit, finish, balance, accessories, and service, because these factors are what is woefully lacking in most knife purchases and ultimately, it is these factors that determine the value of a knife. This point is so important, I've decided to give it it's own page.

Do I use these many kinds of steel? Sure, I do, but the reasonability and economy is sometimes prohibitive. Steels may prohibitively expensive to purchase, tool, grind, and make a knife with. And do you benefit from their attributes? Usually, you'll never realize that benefit, because these specialty steels were not developed for hand knives. They were developed to machine, cut, die press, and form other metals and materials for industry, usually at high feed rates, high speeds, with extreme pressures and heat, sometimes under corrosive chemical exposures. The CPM high vanadium tool steels were created and are mainly used in plastic injection molding machines. Don't think that the steel manufacturers rely on knife makers and knife buyers to produce their income. Knife blade steels are roughly 1-1.5% of the tool and high alloy steel business. Knifemakers just pick up on these steels because makers like to experiment. So they find that they all perform pretty well. I even tried some M2 once to make a knife, the performance was outstanding, but the steel had ugly waves and texture in the surface. I don't know if the user ever sharpened it, because he couldn't. Only a diamond grinder would sharpen it. So there's the limitation of usability and service too. The truth is, if more factories and knifemakers improved those six points: design, fit, finish, balance, accessories, and service, they wouldn't need to hype some specialty steel as a gimmick. Read more about that.

How do I pick a steel type?

Okay, you want details. Metallurgical specifics, because you have a keen need to know just what it is that you're using, paying for, or requesting in the blade steel. Please be sure and read about the Pop steels above, and all of the pertinent information on the FAQ page. Then be sure and read the several topics just below this one, for some more information. Please remember that these steels are the steels I use, and feel free to ask other knife makers about the steels they use and are familiar with.

There are a great number of tool steels, and like most custom knife makers, I have my favorites. The reason a knife maker chooses a knife steel depends on a list of requirements. Often, a client hasn't even considered some of them when he starts the conversation. The word "best" comes up frequently. He wants the best performance, the best durability, the best looking. "Just give me the best steel, Jay," he'll say, and then he'll have the best knife. It's just not that simple. The knife maker must balance many things in his choices, some factors not even considered by the client. Here they are in detail:

• Physical properties: The physical properties of the knife blade (and ultimately the knife itself) can be generalized in a few factors:
  • Hardness: Any good custom maker who heat treats his own blades can produce a very hard blade out of any of the most commonly used blade steels. Hardness is penetration resistance, explained below. It is not the complete standard that a blade is defined by! It is merely the resistance to penetration, which contributes to wear resistance. A maker can make a blade very hard, but if he does, he'd also better make the blade very thick, because it will be brittle, and possibly break if stressed. But who wants a knife blade thick? Only a cold chisel is left thick, not a knife blade, because a thick blade cannot be made sharp. So the hardness has to be balanced with the other factors.
  • Toughness: A tough knife means that the steel is resistant to fracture. The toughness-hardness relationship is explained below, in the section "What About Hardness?" and "Just What is the Rockwell Hardness Scale?" below. Literally, it is the resistance of the crystalline structure to be ripped apart from itself, and that is how a break occurs. Of course you want a blade tough, because a break could be devastating anywhere along the knife blade. The hardness-toughness relationship is under the complete control of the knife maker, within the constraints of the steel alloy used. It is critical to make a thin blade with a tough temper, because a thin cross section must support the mechanical stresses imposed on it. It seems that toughness is completely overlooked in discussions by knife "experts."
  • Wear Resistance: This is the ability of the steel at the cutting edge to resist abrasive wear. What this means to the knife maker and client is that the blade can perform a great deal of abrasive cutting without needing to be re-sharpened. Contrary to popular thought, this is not solely the result of the hardness that a blade is tempered at. Wear resistance is largely due to the alloy components in the steel's crystalline lattice. Large amounts of specific alloying elements like tungsten, vanadium, and chromium all add to the wear resistant capabilities of the blade's cutting edge. When properly heat treated and tempered, the steel contains amounts of very hard particles, chromium carbides, tungsten carbides, and vanadium carbides that all resist wear. But sooner or later, even the hardest, most wear resistant knife blade WILL require sharpening, so wear resistance must be balanced with serviceability.
• Serviceability is my own term, and it refers to the maintenance requirements of all knife blades. Blades have active areas, mainly the cutting edge, the point, and the finish. All of these areas must be serviced and maintained, and the range of care can be seldom or frequent. There are also serviceability requirements of the handle and sheath, and those are discussed on other appropriate web pages on this site. The knife must be suited to its environment; for instance, you wouldn't want to carry a carbon steel blade that can easily rust on marine rescue missions. The four factors of knife blade service are:
  • Sharpening: Even the hardest of knives must be sharpened, but what if the steel is so hard that it cannot be honed or sharpened by hand? The knife must be sharpened in a shop, often with a powered edge grinder and sharpener. One would think that this would make a great tool, because of long cutting edge wear resistance, but what if you're in the middle of dressing out an elk, and the knife edge has reached a point of dullness? What if you're in combat? Many times, it is more important to have the ability to bring a cutting edge to a fine sharpness whenever it's needed than to have a knife that has greater longevity in the edge sharpness, but will take powered equipment to sharpen. I've got some guys that claim no steel is too wear resistant to field sharpen, but those guys think nothing of dragging their blades literally HOURS against the stone. Another issue is the method used to sharpen the steel knife blade. If power equipment is involved, and the feed and pressure rates are too high, the thin steel at the cutting edge may be quickly heated to austenitizing range, to the point of transformation of the steel crystalline structure. Then, even air quenched, the cutting edge becomes hard and brittle and not tempered, can easily chip. This is a seldom mentioned occurrence and danger with power sharpening.
  • Geometry: A blade must have proper grind geometry to be sharpenable. If a knife is ground too thickly behind the cutting edge, it will take many hours of relieving to lower the angle of the edge in order to have a sharp knife. Though this is not always considered a factor of the blade steel type, the blades with a tough structure (resistant to breakage) will lend themselves to thinner grinds, decreasing the effort to sharpen the knife. A thick blade is a dull blade, and only tough steels can be thin steels.
  • Point service: The point is the most important part of the knife blade, and to be truly effective it must be thin. Therefore, the maker must balance the usability of a thin point with the intended use of the knife. The point must be cared for, and the rest of the blade will follow. If the maker has done his work right, the knife user has a long-lived blade point, one that isn't sharpened away to bluntness by a bad or thick grind. If the point is maintained in use, the rest of the blade will follow. You might wonder why I focus on the point in particular. It is because if any part of your knife will fail, it will probably be the point. Steel choices must reflect the geometry, hardness, and toughness relationship of the point and ultimately, the blade.
  • Finish: A lot of knife users initially want to forego a good finish to save a buck. This is possible, but once they realize that it might affect knife blade performance, value, and longevity, they usually rethink that casual attitude. A finely finished knife will simply last longer than one that is rough. A finely finished knife is more valuable in the long term than a rough or poor finish. I talk about the finish in detail on my book excerpt on this very page. The finish desired rests initially in the steel choice, and ultimately and decisively in the maker's skill.
  • Corrosion resistance: A critical component of a knife blade's serviceability, value, and longevity is the ability to resist corrosion. All steels corrode and can rust, even stainless steels. Consider that the cutting edge, which when sharpened, is exposed to corrosive sources in whatever is being cut. The longevity of the cutting edge and its resistance to corrosion is set when the steel choice is made. A mirror polished finish will be the most resistant to corrosion, so the steel alloy choice and finish choice work together to determine the entire blade's corrosion resistance.
• Financial factors: the finest knives are not cheap, and a knife buyer's needs and desires are often tempered by this vital range. The three factors to consider in the financial aspect of a handmade or custom knife purchase are:
  • Cost: All fine steels are expensive, some are very expensive. Some are much more difficult for the maker to use to construct a knife, so their use in a knife blade adds to the overall cost. Certain steels may cut the life of band saw blades, milling cutters, drills, grinding belts, and finishing supplies by three to four times, and the working, grinding, and finishing may take five times as long, so the knife maker must add the cost of all these expendables and time to the knife cost. Some steel types may push the knife out of the price range of the client.
  • Value: The value of a knife blade exists in its geometry, construction, design, and finish, and less so in the materials (I'll bet all you guys wanting the latest pop steels are surprised by that!). Mass-producers of knives, or makers who wish to somehow try to set themselves apart and above others will often focus on the steel type, and less so on their ability to design, construct, harden and temper, and properly finish a knife blade, or make a knife that has real long-term investment and working value. The real value rests in those makers' skills, not just a steel type. A similar comparison would be one of jewelry. A five gram nugget of gold costs the same as a five gram amount of gold used in a fine ring. Which is more valuable? The value is not just the material. It is in the maker's skill, his reputation, his longevity, and his popularity. The long-term value of a knife is also based on the material's ability to retain its appearance and shape, which is related to the finish and geometry. Additionally, the value will be placed upon the knife owner's level of care for the knife. Even the most expensive knives can be neglected, rendering them of little value to collect or use.
  • Size: Not all widths of steel types are available for every knife project in every alloy of steel. When fine tool steels are purchased, they are purchased in bar form. It would be nice if we could take them, like a piece of 5160 standard steel, and form them into the shape we need by forging. Since most of these finer steels can not be hand-forged due to high forging temperatures and necessity to eliminate oxidation to prevent decarburization of the steel, these steels must be worked by stock removal. So the shape of the knife pattern determines the width of the stock needed. Knives like kerambits and khukris have significant curves in the blades, necessitating wider stock, which can be much more expensive. Heavy knives that require thick spines must start as thicker stock, and this, too, adds to the cost of the project. Though some steels can be welded to achieve the needed width and thickness, some can not. Selecting a blade form that requires wide and thick stock may be cost prohibitive.
  • Maker's Name: The knife maker's name is paramount to the value of the knife. In this business, the maker's name carries the weight of all of the maker's history and accomplishments, his following, his expertise, and his future value of knives, both custom and handmade. Though a brand may simply designate a company that manufactures a knife, the maker's individual mark (usually his name) can amplify the value of the investment knife many times over when compared to factory knives or knives made by unknown or unrecognized makers, or knife makers who have not established a long track record of fine knife creation. Consequently, just like big names in fine art, expect to pay more for that maker's knife, because it will ultimately be worth more in the long run.

So, to select a steel type for a blade: here are the considerations: the physical factors of hardness, toughness, and wear resistance, the serviceability factors of sharpening, geometry, point service, finish, and corrosion resistance, and the financial factors of cost, value, size, and name. Seems so simple...

Hey, where is the strength requirement? Read the next topic.

What is a strong knife blade?

Every now and then, I read a post or article that talks about strength as a factor in knife blades. By definition, the strength of materials deals with the external forces applied to elastic bodies. When these forces are applied, deformations and stresses occur, and in extreme cases, failure in the form of bending or fracture. There are a large number of factors to consider in applied forces and metal choices, geometry, time elements, temperature, corrosive exposures, and others, which all have an effect on failure rates. You'll see the word "strong" thrown out there as if it is the all-encompassing final descriptive word to describe metals and performance.

If resistance to failure was the sole measure of a knife blade, why not just leave the blade unhardened, untempered, because that makes it the most resistant to breakage? If you have an unhardened, untempered piece of steel, you can bend it this way and that way, and stretch it, and twist it, and deform it, and guess what? It won't break. It will just deform. Eventually, it will work-harden in the area that it is most deformed, then it will become hard, and more brittle, and then it will fracture. Bend a piece of thin metal back and forth until it breaks. We've all done this; so it's easy to understand.

These same sites will claim that steels with what I consider to have a lower overall performance value as a knife blade are superior to the steels I use. You could claim that 440A is superior to 440C because it is tougher, that is: more resistant to breakage. Guess what? You would be correct! But 440A has less carbon (approx. .60%) than 440C (approx 1.2%). That carbon (twice as much in the 440C) is essential for assuring the hardenability of steels to the levels needed for tools. Raising the content of carbon increases the hardenability slightly, but increases the wear resistance considerably! Increasing the carbon content will have the effect of decreasing the toughness. So if your entire standard for knife performance and strength is unbreakability and toughness, go with the lower carbon blade steel that is not as wear resistant. But who wants a knife that you have to sharpen frequently, a knife that easily dulls? It's all about balance.

What about ultimate corrosion resistance?

Another balance question. There are materials that absolutely will not corrode. Ceramic comes to mind. Titanium is nice. But these are not typical blade steels, and there is good reason. They are several orders of magnitude softer than any good knife blade. These materials are either brittle and unsharpenable (ceramic) or have no wear resistance or low tensile strength (titanium). Though you may see these materials and others (monel, bronze, beryllium copper, aluminum-bronze, and copper alloys) used in making non-sparking, non magnetic tools for special hazardous materials exposures and explosive environment applications, they are not hard, wear-resistant, tough, and durable tools.

What about other, lower carbon stainless tool steels? In my opinion 440A and 440B stainless steels do not make superior knife blades even though they may be a bit more corrosion resistant than 440C. These steels do have at least .60% carbon and are capable of being hardened and tempered, but are not nearly as wear resistant as 440C.

One may claim that CPMS30V, CPMS60V, and CPMS90V are slightly more corrosion resistant than 440C, but since they can not be mirror finished, their rough surface may actually accelerate corrosion (see my book clip on finishes below). There are a host of other metals used in knife blades and a large variety of performance options, so nothing is set in stone here. That is why any maker worth his salt will use a variety of steels, and yet still have his favorites.

What kind of steel are you "pushing," Jay?

I had a good laugh when I saw on another site that I've been accused of pushing a particular type of tool steel by self-proclaimed experts on knife blade steel (By the way, when you see these sites, ask how many knife blades the expert has actually made. Then ask to see a list of military and professional clients he's made knives for. Then ask to read the testimonials of support submitted by his military and professional clients).

I don't push any particular steel. If you have a special steel you prefer, please, by all means, let me know why, and I'll make a knife out of it for you! I don't have an agenda about the steels I use, I just have my favorites. There are new ones all the time, and you might be surprised to find out that I've tried quite a few. I don't get kickbacks, or promotional payment, or some kind of benefit from suggesting a particular type of steel. I also am very clear about the steels I do use, and if you have a particular and specific question about the type of steel used in a knife I make for you, by all means, ask! Please don't ask about steels other makers use, feel free to ask them. Want to know what is being overlooked by experts arguing about steel types? Fit, finish, balance, design, accessories, and service.

Why do you go on and on about steel types?

On one discussion forum, my little wisdom box about web sites and forum discussions going on and on about steel types and ignoring the overall properties, design, and value of the knife was noted, referenced, and repeated. It got a lot of agreement as most knife makers realize the truth and impact in that statement. I appreciated the posting and reference, as the little box that appears frequently on my site is always important to remember.

Then one genius attacked this very page, claiming that I go on and on about blade steels on my own site, and hinted at the hypocrisy of the statement. I didn't bother to respond, as this guy's amateur knives speak for themselves, and bolster my very claims.

Just to be clear about going on and on: This is the "Blades" page. This is where I go on and on about steel types, because modern knife blades are the subject of this entire page. Though I briefly mention steel types on my FAQ page, on no other page of this site (over 270 pages at the time of this writing) do I elaborate on knife steels. I have many pages dedicated to individual knives, specific groups of knives, handles in general, and even pages dedicated to specific handle materials, knife sheaths, and even display stands. But yes, in a way this genius is correct, I do discuss (on this one page) knife blade steel types and properties in detail.

Welcome to my Blades page, which at the time of this writing is the most popular page on my site, getting tens of thousands of hits a day. Please bear with me while I discuss the subject of knife blades, blade geometry, and steel types. To bring some reality to this whole topic, please note that less than one fourth of the topics on this very page are about specific steel types, because as I've stated again and again:

What are the steels you do use, don't use, and why?

Here is a detailed list of the steels I use, and some I don't but get asked about frequently, along with information, data, and my reasons for using (or not using) them for knife blades. I won't go into the specific alloy components and percentages, as they are readily available all over the Internet and from common references as these are not mysterious or secret process steels, these are steels that are listed, detailed, and defined by AISI, SAE, and ATSM. They are industry standards for a reason; they have a proven and long standing track record of dependable application in industry; there benefits are well known, and they typically have to endure much more rigorous and detrimental service than a knife blade would ever see!

440C High chromium martensitic stainless tool steel is chosen for it's machinability, ease of care, and long lasting value. Actually classified as SAE 51440C, the description in the machinist's guide is: "This steel has the greatest quenched hardness and wear resistance upon heat treatment of any corrosion or heat-resistant steel." 440C is one of the most often used knife steels in the handmade industry because flat out, it's a great steel. It is my most often used steel, and it has a fantastic reputation of reliability and value. It's one of the most stain resistant of the stainless tool steels, with up to 18% chromium and up to 1.5% carbon. Not much will corrode this blade steel, and it's tough and hard and wear resistant. No tool steel is rust proof, but 440C is about the best you can get for fine custom knives because in addition to being a high chromium tool steel, it can be smoothly and brightly mirror polished. For long lasting beauty, it's the choice for most of my knives, and for nearly all my high end and sculptural pieces. 440C has and retains high investment value because of its capability to be highly finished and polished, and keep it indefinitely with little care. It is a beautiful high chromium steel. 440C is used in more of my combat knives than any other of the steels I use because it is proven to work well, limit corrosion, and be strong and tough enough for combat tactical and rescue operations, yet it can be sharpened with only moderate effort. There is a reason that one knife blade analysis and testing site claims: "Grade 440C is capable of attaining, after heat treatment, the highest strength, hardness and wear resistance of all the stainless alloys."  440C is a great steel; Just look at some of the finest knives made by some of the best makers in the world. Many are using or have used 440C. It is a gorgeous steel, with a bright bluish-chrome color when polished. When you want an investment piece to have a high finish, hold it well, and hold it for decades and decades, 440C is the way to go.

ATS-34 high molybdenum martensitic stainless tool steel is essentially the same as 440C, but 3% of the chromium has been replaced by molybdenum. So it's a little less corrosion  resistant, but it's tougher. That means it's more resistant to breakage. This is one of the high "chrome-moly" steels everyone's heard of. The finish can be a bit smoother than 440C, but I've also had some that is grainy. Because of the additional toughness, a thinner cross section can be ground for blades like double-edged tactical knives without sacrificing strength. For the knifemaker, it's also harder to work with: harder on tools, abrasive belts, and is more expensive. Being not as corrosion resistant as 440C, it may not hold its investment value for as long, but we're splitting hairs here. It should retain its beauty long after you and I are dust, with minimal care.

154CM is essentially the same as ATS-34, but is a domestic version. I don't use it anymore because it has a reputation of  having pockets and voids in the steel, making it unusable in the custom knife field. I've never discovered any pockets or holes in ATS-34. Other makers may argue, but I won't take a chance in working up a blade, and finding a hole in it!

CPM154CM is similar in composition to 154CM above (and similar in composition to ATS34), but is a crucible particle metallurgy tool steel, made of sintered alloys formed together. This is Crucible Steel's version of the 154CM, made to better tolerances and, with the crucible particle manufacturing process, an even distribution of alloying elements. It is much like ATS-34 in that it is a high molybdenum stainless tool steel, and very tough (resistant to breakage). One might ask why even use ATS-34, since the two are so similar in composition. The CPM154CM steel is expensive. Very. And sizes are limited. The cost of making a knife in this material and finishing it are more expensive, so one must question why they might need it. CPM154CM does excel in one area, and that is finish. This steel finishes absolutely beautifully. The mirror finish is even, smooth, and uniform with no crystalline pattern that can be seen with the naked eye. My recommendation for using this steel is on a high art or investment grade knife of fairly standard sizing, where a supreme finish and high toughness are needed. It engraves well, but does not etch well, as standard mordents create only a gray finish, not dark gray or black which is a testament to its high corrosion resistance. This steel is also hard to sharpen and may require motorized equipment to work up a good edge.

O1 Oil hardening high alloy tungsten-vanadium tool steel is a highly underrated yet superb oil-hardening cold work tool and die steel and is a high alloy tungsten-vanadium tool steel that can be made tough, hard, and extremely sharp and wear resistant. Please note that not all O-1 by all manufacturers has the same alloy content! Some versions contain no vanadium whatsoever, and those versions of the alloy do not benefit from the advantage of vanadium carbides that increase wear resistance. The O-1 I use is a tungsten-vanadium version, and has high wear resistance. O-1 blues well, so tactical models and art pieces that require a dark blade look fantastic. It's fairly easy to work in the annealed state, so prices can be kept reasonable. Polishing it is difficult, and requires a different regime than the stainless tool steels. O-1 will rust if not cared for, but it's a great steel, maintains an incredibly sharp, fine edge and is relatively easy to sharpen in the field.

Plain carbon (standard) steels: These are the typical steels used by many knife makers and are classified in the Machinists' Guide as Standard Carbon Steels. These are steels like 1095 and 5150 that are fairly common on hand-forged knives. They are used because they can be hand-forged and have a relatively low critical temperature and are easy and forgiving to work with. I rarely use them because there are so much better alloy steels on the market that will offer increased wear resistance, increased corrosion resistance, and higher toughness at a higher hardness than plain carbon standard steels.

D2 cold work high carbon, high chromium die steel: is the highest carbon alloy tool and die steel (thus the "D" designation) typically used in knife making. It has 12% chromium so it doesn't resist corrosion as well as high chromium tool steels and will rust if continually exposed to corrosive moisture, acidic fluids (like orange juice or blood), so requires more attention. But at 1.65% carbon, it can be made very hard, and very wear resistant. The polished finish on D2 can be somewhat mottled with an orange peel appearance. This is due to chromium carbides forming in the steel during heat treat, the very thing that makes this steel so wonderful (most steels form iron carbides). Please note: some manufacturer's versions of D2 do not exhibit the orange peel granularity in the polished finish because they are made with a higher sulfur content. These high sulfur versions are easier to machine and are designated "sulfurized D2." D2 is very hard to work with, expensive, downright malicious to abrasives, resistant to cutting and milling and metal fabrication. So it's usually used for extreme use knives. It has a reputation of holding an edge forever, and being impossible to sharpen. The reputation is well deserved. Most people cannot sharpen D2 in the field, or without motorized equipment. One of the seldom mentioned properties of D2 is very high depth of hardening and stability of shape. In the AISI Service Properties details, D2 is designated at the top of the scale for these properties, so intricate shapes can be created and maintained, although D2's machinability is very difficult and that creates additional expense. Sizes are also limited and the steel is very expensive.

CPMS30V, CPMS60V, CPMS90V (sometimes called S30V, S60V, S90V, 440V): It's important to see the CPM designation in front of these steels when their use is claimed by makers and manufacturers. It stands for Crucible Particle Metallurgy and means that the steel components and alloys are mixed and inserted in powdered form into a die, and the steel billet is formed under tremendous heat and pressure, similar to sintering of metallic components. This allows an even distribution of alloy elements that might not be possible by traditional methods. The 30, 60, and 90 designations refer to approximately 3% and 6% and 9% of vanadium in the alloy. Vanadium is used to contribute to the refinement of the carbide structure, and thus improves the forgeability of these steels. It has a very strong tendency to form a hard carbide, which improves both the hardness and the wear properties of these steels. However, a large amount of vanadium makes the grinding of the tool steel very difficult. These steels will eat up grinding and finishing belts at three times the rate of 440c, and are much more expensive. The downside is that the price of machining is high, the price of the material is high, and the availability of sizes are limited. These steels, when properly hardened and tempered do create a very tough, very hard blade, slightly tougher and harder than 440C. So hard and wear resistant are they that sharpening is extremely difficult without motorized equipment. Sharpening may also take many steps to achieve a very fine edge, so they're not practical for knife users who might need to sharpen these steels in the field. One of the main and seldom talked about (elephant in the living room) issues is the inability to be properly finished. Since most makers just rough grind and hand-sand along the blade length, it doesn't matter, but that is not how a fine investment grade knife is made. None of these high vanadium stainless steels can be mirror finished to any reasonable degree of economy or repeatability. When they are brought up to fine finish and polishing, the finish smears, fogs, and skids (polishing terms), and brings out waves of uneven texture. Frankly, these steels are best left sanded or bead blasted. The craze over these steels is valid, until a client asks for one to be mirror finished for investment value and high corrosion resistance. I do use these steels, but they are not my most popular because of these issues. They can be etched, with special mordents and pickles to achieve some interesting artistic finishes. CPMS60V manufacturing has been suspended currently, so any available stock in it is older. These steels are very expensive to purchase and work, and sizes are limited.

L6 is a low alloy special purpose tool steel that I get asked about periodically. It's most frequently used on saw blades and in blanking, forming and trimming dies and feed rollers where toughness and resistance to shock loads must prevail over wear resistance. Toughness is resistance to breakage or fracture. So, you can imagine that a band saw which has to flex a lot would need to be tough. It has some applications in cutlery where that toughness is needed. Unfortunately, it has no corrosion resistance and quickly and easily rusts. So there is a large and looming problem here. Knives that require toughness, like fillet knives or knives that must spring and bend (e.g. kitchen cutlery) would do well to have the toughness of L6, but it rusts so easily that it is not a good selection for this purpose. Most modern knives have some corrosion resistance, and most knife owners insist on high wear resistance (usually higher hardness overall) so the use of L6 is limited. If I have to use a steel that can rust in a knife application, or must be blued, I usually opt for O-1 because it has tungsten and vanadium and has a greater hardenability and wear resistance than L6. For flexibility with high corrosion resistance, 440C is a much better selection, when tempered back for increased toughness.

S7 is a shock resisting tool steel, and I occasionally get asked about it for knife blade use. Shock resisting tool steels are made with low carbon content (.5%) for increased toughness (resistance to breakage) at the expense of wear resistance. Please remember that all S-steels (S1-S7) have a very low wear resistance. They do not make good knife blades, and would need to be sharpened often. Shock resisting tool steels do have their uses, in example for air chisels, forming dies, casting dies, and shear blades. In my opinion, these are not good steels for knife blades that will need wear resistance at the cutting edge. Though some of the shock resisting alloys have chromium, they are by no means stainless or corrosion resistant.

These are the main steels I use and some that are asked about, and I also use other specialty steels. I might add to this detailed description as time goes on.

Choosing a knife blade steel

A choice of blade steel does not need to be daunting task. Since all of the blade steels I use are fine tool and die steels, all high alloy well designed engineered steels, every component, every arrangement has been detailed. You know just what you're getting, without a lot of hype and bull. So many confusing recommendations, suggestions, and so much hype is on the internet and in magazines about special steels that this has become a sore point with most knife buyers. Everybody hypes their steel, and nobody looks at workmanship, design, fit, finish, service, and accessories, much less the reputation of the maker. Look at my "Knife Points" page and you'll understand exactly what I mean. Most knife users will never use a knife brutally enough to actually notice the difference in performance, but of course, every knife client wants the best steel for his purpose and his money.

The chart below is a general guide only, and the properties of these tool steels can be adjusted in the grind geometry, and the hardening and tempering. All these high alloy steels outperform plain carbon steels, non-tool steels, or damascus steels. As you can see, everything is a trade-off. If you want to go with D2, for instance, you will have a hard time field sharpening it, and it is very expensive, and does not have a good finish. For high art pieces and investment pieces, 440C is usually used, because of great corrosion resistance and finished beauty. Only O-1 in this list can be hot blued, and is easily field sharpened, but it rusts at the first opportunity of neglect. You might want the tough, hard, supreme wear resistance of S30V and S90V, only to find out they can not be mirror polished, so are not suitable for long term investment knives. Corrosion resistance can be very important if the knife is used in the field of combat or tactical operations around corrosive fluids or water. Remember, the edge itself can corrode, and become dull from corrosion. This is probably another reason why my most popular knife steel is 440C.

An interesting thing to consider is that manufacturers claim that CPMS30V is more corrosion resistant than 440C. But this claim assumes that both steels have the same finish. Since S30V, S60V, and S90V can not be mirror finished, there is no way that in a bead blasted or rough satin finish they are more corrosion resistant than a fine mirror finish on 440C. Read why below.

The chart demonstrates why there are choices, to allow the knife client and knife maker to reach an agreement on the steel's properties suited to the application. These are only my main steel types. There are other steels, of course, and I'll add their properties as I get requests.

Are all custom knife makers alike?

Of course not. They run the full range of quality from low to high. Some flat grind, some hollow grind, some stock remove, some forge, some assemble kits. You'd better be educated about the difference if you don't want to get ripped off. Here are some points to look for:

• Is your knife maker well known and established? Unlike factories who use a name from another time when they actually made a superb product, the knife maker must establish his name over decades of production. I'm not saying that a new maker does not make a fine knife; sometimes he does, it's just that longevity in this business is created one knife at a time, over decades. A beginning knife maker or craftsperson can work for a month and produce a pretty fine knife right out of the blue (or from a kit), but that is altogether different that a full-time custom knife maker who produces hundreds of knives, every one of them superior to most other handmade knives, year after year, for decades, and has the testimonials from professional knife users like the active duty military, police, professional chefs, professional hunting guides, and collectors to back it up. This is generally someone who knows knives, or he wouldn't be in business. His name is etched, stamped, or carved permanently into the steel, and every knife with his name on it carries his reputation.
• Does the maker serve professionals who use fine knives daily? Does he make for professionals who trust their lives to his workmanship and product (like military in combat, police and SWAT teams, or CSAR rescue teams)? Has he done that for years? Decades? Can he prove that to you, show you his work, illustrate by commentary and testimonials? Does he have an actual photographic archive of hundreds or thousands of his knives for proof? Are his knives sought out by collectors for their own originality? Do his knives increase in value over the years? Is he charging more every year for his work? If he does, and he has little inventory, it's a good bet that his knives appreciate dramatically.
• Look at the individual knife closely. Is it properly finished? Does the blade have grind marks, sanding marks or waves? (More about blade finish) Are there any visible gaps, scratches, bumps, waves, or rough spots in the handle? (More about handles) What does the overall appearance of the knife suggest? Is the blade size in balance with the handle? Are there thin areas where the whole knife might be weak? Did the maker fully taper the tang? Is the filework or edgework accurate, balanced, and square? Does the sheath match, and is it well made? (More about sheaths) Pick up the knife. Does it feel good in the hand? Is it full, smooth, and solid? Is it balanced, easy to manipulate, and comfortable? Does it fit well and snug in the sheath? A maker should have no problem with you handling his knives, in fact, he should encourage it! I've conveniently put handles on each and every one just for that purpose...
• Here's an important one: Hold the knife with the edge up, the point aimed right at the space between your eyes. Now cast one eye down one side of the blade, and the other eye down the other side of the blade. This may take some practice, but it's worth it. You'll get a clear picture of the grind lines, where the hollow grind (or flat) grinds meet the blade flats. These lines should match as closely as possible. By the way, looking at knife this way scares a lot of knifemakers, because they know you'll be able to see any irregularity, and it also shows that you know custom knives!
• Is it sharp? Most people can lightly touch the thumb or finger to the cutting edge and tell. There should always be a wide-eyed amazement when this happens!

How does the buyer know the reputation of the maker?

There are several ways to verify the knifemaker's reputation. Who does he make for? He should have that right out front, for all to see. He should have no problem telling you who he makes for, what they use the knives for, what the knives are valued at. Does he have a past history of shows, membership in professional knife organizations, or publications of his work? Does he have a professional website or archive of his past works? Where are his knives now? Are any in museums, collections, or displays? Can he give you any names of people who have used his knives and like them? Can you see pictures of his knives?

These sound like simple, obvious questions, but you would be surprised at how many clients are distracted, played, and conned by knifemakers. Here's an example: I attended a show once and my table was next to a female knifemaker, who immediately claimed to a prospective client that her family had thirty years of knife making experience. She was in her early twenties and laid claim to her family's experience as her own! Those years of experience were not apparent on the knives laying on her table, as they were big and blocky and badly finished and out of balance and ugly. Then, she gave the prospect some BS about the mystery of heat treating, how it was a special family secret handed down through generations. I bit my lip, knowing that heat treating is specifically described and prescribed by the manufacturer of the steel, that it is right up front in all engineering specifications for all knife steels, that it should be clear and simple to the client that the maker is treating the steel just as specifically as the manufacturer requests for the intended use. But the worst part is that she giggled and feigned interest in the client, smiling and flirting like a prostitute, which kept him looking at her more than the knife. The truth here is that some men are easily swayed by the attention of a young lady. He'll walk away with an overpriced hunk of junk, and the memory of a brief encounter with a con. Is it worth it? I wonder how the line of BS would have gone down if his wife was standing beside him-

The moral here is look, look, look.... at the knife. The knife itself should be your focus of attention. Yes, you want to know the reputation of the maker, you want to know he's had years of experience and trustworthy clients. Still, take some time and examine the knives or the photographs very closely in front of you, they should speak for themselves. Listen to what the knifemaker says; does it make sense? Can the knifemaker answer your questions with intelligence and dignity?

That brings me to another professional aspect of the knifemaker: his appearance and attitude. Do you like buying from a loud-mouthed polyester prince used car salesman? Are you comfortable with a cowboy all duded up with his best brushed felt range hat and high boots more suited to stomping through cow dung than presenting fine work? How about that guy wearing a tee-shirt with rude graphics and holes in it and a goofy, grimy baseball cap? Are these professionals that you would hand your hard earned trust over to? The reason I include this topic is because every knife or craft show has this type of knife maker. So, does the knifemaker look, act, write, and present himself as a professional including here on the internet? Now, don't get me wrong; if someone comes to my studio and shop, and they catch me with my full-face respirator and metal swarf-covered coveralls and work boots covered in wood and rock dust, I'm still a professional. But I wouldn't be caught dead at a knife show in that get-up. It's just not professional.

Simply, there is no miracle about making knives. Making knives is perhaps the oldest profession around. Yes, before even that one. Men have made knives for literally millions of years, for without a blade, early man would have starved. It is an honorable profession, if presented honorably. There is no great mystery, just practiced skill and determination. There are no mystical secrets to steel ingredients, to heat treating, to knife or blade shape, geometry, or materials. There is no enigma in the blade, no mystical materials; we don't quench in the blood of our enemies, there is no romance to the cutting edge, only artistic interpretation. No sword or crystal has magical powers, steel can't cleave stone, and a suitable dagger will not allow you to fly. Fine knives come from trained and practiced hands, not from a hidden tomb in a mountain. They are tools and sometimes works of art made by people like me who love to make them.

I take this business seriously; it is my full time professional job. I respect my clients and share their interest and love for knives.

What is blade geometry, and why is it important?

Blade geometry is most easily interpreted as the three dimensional view of the knife blade. Most often, the flat perspective is used in examining a fine knife blade, the same view presented in a photograph of the knife. You can see the grind profile, the general shape, the contour, and any additional agents such as serrations, clips, false edges, choils, and filework. This view, however, lacks the third dimension which is cross-sectional geometry. How thick is the knife? How thin is the cutting edge? Is the grind matched and balanced on both sides? Let's examine some of these points:

The thickness of the knife at the spine (which should be the thickest, strongest part of the knife, not the handle!) must be strong enough to support the leverage applied at any point along the knife blade within reason. I accent reason because a balance should be met between thinness of the cutting edge and the weight and thickness of the spine. For example, you probably couldn't break a blade that had a spine of 5/16" (.3125" or .8 cm) thick. But this would be an extremely heavy knife (more like an axe, actually). Now, to put a fine, thin cutting edge on such a beast would require a deep hollow grind, or a long flat grind, and for proper geometry that would necessitate a very wide blade. Some makers actually make this kind of knife, so there evidently is an interest in them, but you won't find them on my site. Mountain man knives seem to lean toward this geometry. I've never met a man that used an axe to skin a deer, but I haven't met everyone...

The most important part of the knife's geometry is the cutting edge. It must be thin on most knives: thick enough to support the intended use, but thin enough to allow a low sharpening angle for aggressive cut. So the custom knifemaker walks a balance between strength and thickness, and sharpness and thinness. Learn more about thinness and sharpness and the cutting edge by linking to "Razor Edge Sharpening" on my links page.

For comparison, let's first examine the flat, taper, hollow, and convex grind. Here is a view of the cross-sectional area of the ground portion of a blade.

This graphic is a slightly exaggerated cross-sectional view of the four basic knife grinds. The descriptions below are linked to complete descriptions and graphics that describe each grind's type of cutting edge, longevity, and limitations.

The flat grind is an exact wedge. The advantages: easy to grind using minimal equipment, thin cutting edge, plenty of support for cutting. Disadvantages: as the blade is sharpened, the cross-sectional area quickly becomes thick, necessitating regrinding or relieving of the cutting edge.

The taper grind is a lightly convex wedge. Some guys call this a convex grind, and some call the grind convex when what they are talking about is the cutting edge shape itself. Advantages: used on a knife, a thin cutting edge, stout cross sectional area good for chopping, tough profile with plenty of meat (steel) to support the edge. This is the only grind suitable for a very thin blade (less than .0625"). Disadvantages: sharpening the blade in continuous use renders a thick cross-sectional area, requiring relieving. On a thin blade, this is okay, because in sharpening, the taper is ground away. Not a very attractive grind, it looks washed over. Many makers and manufacturers use this grind because it's one of the easiest grinds to construct. Any slack belt grinder or flat platen can make a decent taper grind.

The hollow grind is hollowed out by a wheel, the grind size indicates the circumference of the grinding wheel. Advantages: The hollow grind can be made incredibly thin, in fact, the sharpest of the blade cross-sectional areas shown. As the blade is sharpened repeatedly, the blade will remain thin well into a third or more of it's grind, sometimes half, without needing reground, only sharpened. Disadvantages: blade behind the cutting edge is thin, not much metal to support chopping or abuse, must be constructed with finer tool steels to support thin edge with toughness at high hardness. Special equipment and lots of skill required to grind and polish correctly.

The convex grind I refer to in this document is an axe grind, specifically referred to in this paragraph as applied to axes, large machetes, chopping tools over 3/8" in thickness. I'm not talking about a knife. Note: What most guys are calling convex today is a taper grind. If you insist on calling a taper grind a convex grind, please read the details on taper grind above.

Knife blade relief face angle and the cutting edge

Usually, the only owner maintenance that requires more than preservation of the blade is sharpening. Sharpening is not a mystical secret closely guarded by faceless men in dark robes hiding behind an altar of grinding wheels, angled rods, whetstones, and diamond files. It is simple geometry. The thinner the blade, the less the relief angle, the sharper the blade. The relief face is the flat, abraded line you see between the actual cutting edge face and the blade grind. So the knife user has to abrade away the metal at the relief face to keep the angle low, so his edge may be sharpened. For sharpening expertise, please check out the "Razor Edge Sharpening" link on my links page.

So it comes down to the thinness or thickness of the relief. The thicker the relief, the more chisel-like the angle of the edge (bad), the thinner the relief, the more razor-like the angle (good). The blade grind geometry dictates the thickness, and there is a huge difference between factory and well-made handmade knives. When a knife user first purchases a factory or poorly ground knife, it may be reasonably sharp. What happens after he uses it, wears the edge, and sharpens it repeatedly will demonstrate why grinds are so different. How many times have you had a factory knife and complained that after three sharpenings, you can't get an edge on it because it's too thick?

Grind geometry comparison

Take a look at the illustrations below, and you can see the differences in the size and thickness of the relief faces, and ultimately the angle of the cutting edge face, and which grind geometry supports the thinnest cutting edge.

The Flat grind:

The cross-sectional geometry becomes thick after several sharpenings, leading to large relief faces, and heavy blade thickness. Though the flat grind is very strong, the knife must be reground at the relief face repeatedly in order to maintain a thin cutting edge. Regrinding to make the blade thinner can usually only be done by machine as the relief face extends deeper into the blade, and the blade finish may be ruined. The flat grind is used often on thin folding knives and kitchen knives, and even then becomes thick after several sharpenings. Its advantage is that there is a lot of metal behind the cutting edge, and the knife lends itself well to chopping or high impact use. But because it's a straight wedge, it will often embed itself into materials like wood and stick there, unlike a convex or axe grind which splits apart the wood. It is also a heavy blade, with unnecessary thickness in the midline of the blade leading to the spine.

The Taper Grind:

The taper grind is usually used on thin knife blades, .0625 (1/16" or .16 cm), or on false edges, clips, swages or knife blade components. You might also find this grind on thicker factory blades. Some guys call this a convex grind, but a convex grind is a typical grind found in an axe. See the previous topic. The taper grind is easy to grind and finish, and that is one of the reasons it's often hyped and recommended. It is far easier to taper grind a knife than to hollow grind one. The taper can be ground on a slack belt, or with an automated pass surface grinder under computer numerical control. This lowers the overall expense of grinding. Finishing is easier too, as crisp, clean defined grind lines are not made, so less skill is required to make it. You might read that the taper grind is preferred because it is stronger. Strength in the blade is determined by many factors; see the topic below. In a taper grind, the grind is usually along the blade rather than perpendicular to it. This is how most factory kitchen knives are ground. When it is sharpened, it gets much thicker, but this is usually not much of a problem because it is used on thin blades. I use it on my thinnest blades, like fillet knives. It is not a grind for thicker or heavier knife blades unless you want to use your knife to chop down a tree.

It cuts textiles, wood, and foods adequately, but has much more resistance to cutting than a hollow grind.

 

The Hollow Grind:

The hollow grind is universally accepted as the sharpest, highest valued knife grind. Historically, the hollow grind has the highest value across many cultures. The deserving reputation is due to the difficulty of designing, constructing, grinding, and finishing the hollow grind accurately. If executed well, the hollow grind possesses the thinnest cross sectional area and allows a lower relief angle, smaller relief faces, and an overall sharper edge. As the edge is used up with repeated sharpenings, it remains thin, sometimes well into the midline of the blade, offering the greatest longevity of any knife grind. Because the blade steel is hollowed out, it leaves a fully thick spine supporting the blade for good strength, while reducing unnecessary weight. While it can be made thin and may not support heavy chopping, with careful planning, design, and execution by the knifemaker, can be made well enough for light chopping. For example, my military clients who require thin, sharp, but tough and strong blades for Combat Search and Rescue insist on hollow grinds. For investment knives and value retention and appreciation, the hollow grind is considered the most beautiful. It is a challenge to execute accurately and mirror finish well.

Because the hollow grind is usually thinner, it's easier to sharpen. Less time can be spent as relief faces are small, and there is less blade material to remove to bring up an edge.

Another important advantage of the hollow grind is resistance within the cut. When a knife is used to slice through tough, abrasive, or resistant materials, it is also wedged into the cut, creating friction. If the blade is thin, less material is displaced and there is less friction. A thicker blade (flat ground, taper ground, or convex) must displace more of the material in the cut, and therefore has greater friction.

Ultimately, the knife use dictates what geometry is used in making the knife. Only a handmade knife and custom knife maker can adjust his grinds and profiles to the individual user or style of knife. He can offer the variation, the diversity of materials, and the balance between geometry, hardness, and temper that each different blade geometry requires for the knife's specific use.

Grind geometry unrest!

I happened to see my name coming up in a popular knife forum on the internet, and guys were piling on defending their favorite knife blade grind geometry. They didn't like what I had to say on my site, and were fiercely defending their opinions. It's curious that rather than ask me outright to clarify my opinions, they chose to comment on a forum...
I felt compelled to respond:

Want to know more about obsessive-defensive knife owners? I've given them their own section on my Business of Knifemaking page at this bookmark.

What about blade friction when cutting?

Any knife grind that creates a thin enough edge can be made sharp, and can be made to cut various materials. The shape of the blade does matter when it comes to cutting friction, and resistance while the knife blade is deep in the cut. Just what grind has the least and most resistance to cutting friction on the sides of the blade?

I read a comment once where the writer had claimed the convex grind or rolled edge has less friction because it only contacts on a tangential point. This would be true if only the material being cut has no give, no movement, no springiness to it. Also, as that material is cut, it would just open up, not pinch, but contact rigidly at one single point. But just what material would that be?

The fact that you are cutting instead of sawing means that you are not removing any material from the cut. In a saw cut, the teeth on the blade have a wider kerf than the blade itself, so that is why the saw blade does not stick and create friction in the cut. Knife blades have no kerf, no material is removed in the cutting action, so the material being cut will, of course, try to fill the cut, and push against the sides of the blade. The thinner the blade, the less friction and resistance. A taper or convex grind  or rolled edge will push outward on the material being cut at a greater amount than any other knife grind cross sectional geometry. A flat grind will press less, and a hollow grind offers the thinnest blade and the least friction of any blade grind. This may seem like a small item, but in combat knives, where great force is delivered to the blade edge, and tough fibers, textiles, and tissue create great friction in the cut, any advantage is welcome. This is another reason nearly every military combat professional that I make CQC and CQB knives for requests hollow ground blades, whether the knife is straight, swept, or recurve in profile.

The grind is more than the cutting edge!

Yes, it's true, there is much more to the knife grind than the cutting edge alone. Please take some time to familiarize yourself with the terms on my Knife Anatomy Page. In my upcoming book I'll go into much greater detail, but the grist is this: the grind has a termination (plunge) and a lead-off (at the spine). These two areas are immensely important to the overall strength and usability of the knife blade and its longevity and value. The grind termination of a flat grind is often very squared off, as it is the easiest way to form this area. Guys even call it a shoulder which is supposed to justify their practice in squaring-off the termination, but nothing could be worse than sharp angles in this area! Also the shoulder is a completely different component on the tang of a hidden tang knife or sword.

Think of how the grind termination is formed on both sides of the knife. If you have a deep grind which cuts through and removes most of the blade thickness at that point, the knife will be much more subject to breakage right there at the grind termination! This is why I think it's critical to have a gentle, curving, sweeping grind termination, so that stresses at this critical point are reduced, and spread over a meaty, thick part of the spine. By the way, nearly all factory knives have sharp grind terminations, leading to extreme weakness in this area.

The second component is the lead-off. The most used part of a knife is the first two inches. The lead-off and how a maker handles this area is important to point strength, point sharpness, and point longevity. Please remember that the point is the weakest part of the knife. Any knife point can be broken. To prevent breakage, a lot of factories and makers leave the point very thick with a short lead-off. Sure, you have a thick point, the point is stronger. But what about after you sharpen the knife three or four times? With a thick lead-off, sharpening will yield a cold chisel-shaped geometry, which will make the knife user apply more pressure in the cut or piercing activity, and more pressure applied will hasten point breakage or slippage, causing a nasty accident. In order to compensate and thin the knife sufficiently, steel has to be relieved behind the cutting edge, and the profile shape of the knife can be dramatically altered when this is done.

Some makers tend to grind knife blades thickly, some grind them thin. I'm a fan of thinner blades, because of longevity, cutting geometry, and value. I do not recommend whacking down the oaks in your back yard with one of my knives, because a knife is for cutting, and an axe is for chopping. The modern knife user knows this, and often carries a small camp saw for just such a purpose.

How sharp is sharp?

Often, when knife owners get defensive about their knives, they leap to the time tested tradition of "my knife is sharper than your knife." This is rooted in the boy-child game of "my marbles are brighter than your marbles," or "my dog is bigger than your dog," or "my dad can beat up your dad." Their concept is that if a knife can be shown to be sharp: really sharp, scary, extremely, shiver up your spine sharp, you will be amazed, impressed, and awe-struck by the knife itself. Then, they can claim the grind, the steel, the knife is (of course) much better than others.

The method to accomplish this is always the shave the hair on your arm trick. They even call it "popping the hair off your arm," or claim the edge "just pops the hair off." This may be based on the concept that the hair is so terrified that it leaps off the arm in fear when it sees the knife blade coming, rather than suffer the certain severing with ultra-keen steel that will undoubtedly occur.

There is a great demonstration by a world famous sharpening expert (whom I greatly respect) of him taking a dull, double-bitted axe and honing it to razor sharpness in minutes, and shaving a full beard off his face. Yep, when I need a good close shave, I head to the shed out back and grab a shovel, hoe, or even a maul and take it to the bathroom with a hand full of Barbasol®. A retractable blade utility knife with a brand new blade is pretty sharp, definitely sharp enough to pop the hair off the arm or face, and I shave with those too, but not when I want to impress the in-laws visiting for the holidays.

I can take a piece of brass, phenolic, or china plate and make a cutting edge out of it. Some of the sharpest cutting edges ever in existence were obsidian flakes, and I guarantee they are much sharper than broken glass when flaked right. Ask any flint knapper what he thinks is a sharp edge, and your knife's cutting edge may cower in comparison. But does the edge alone make a great knife? Of course not.

These are but a few examples of the obsessive-defensive knife owner. Want to know more about obsessive-defensive knife owners? I've given them their own section on my Business of Knifemaking page at this bookmark.

How do I sharpen the knife?

Factories don't really know what you need to maintain a sharp cutting edge, and they don't even send the knife from the factory with a sharp edge. In fact, most people have never even seen a knife with a truly sharp cutting edge, and are astonished and frightened when they drag their finger over one. I've seen this again and again, and it's really sad. Mostly, factories use a fine, hard buffer and light abrasive to quickly rough in an edge, then out the door it goes. This they often call a rolled edge, and even boast (falsely) that is sharper than an accurately faced edge! It may seem sharp, but is easily and quickly dulled, and does not possess a geometry that will allow the user to re-sharpen the blade with any reliability, the only service the knife owner is responsible for. So the knife dulls, and a dull knife is a dangerous knife, because the user will apply more pressure to achieve a cut, and then he will slip. A slip is a knife out of control, headed at high speed towards a soft body part; most cuts are from slips. When you have a sharp knife, you're cutting carefully and slowly, you have great respect for the edge, and the experience thoroughly enjoyable. Just hand someone a sharp knife to cut their food, and watch their whole demeanor change. It is truly pleasurable to use a fine, sharp knife!

Your field sharpening will differ from my initial edging that I put on in the shop, though not by much. You can tell from the previous sections on blade and edge geometry and the relief face angle and the cutting edge that the proper angles are important. The first angle to define on the knife is the edge relief face, that is the removal of the metal behind the cutting edge. In the shop, I do this on a very slow speed belt grinder in two steps, my first cut is with a worn 60 grit ceramic belt, and a second pass with a 220 grit ceramic belt usually defines the relief face angle and cuts a clean, clear line.

Edge relief in the field is more difficult and arduous. Some steels, like CPMS30V, CPMS90V, and D2 can not usually  be effectively relieved (and thus sharpened) in the field. Diamond stones can help, somewhat, but if you're removing a large amount of the face, a tiny stone or diamond is not capable of this, and you're unlikely to carry a two by eight inch bench stone into the field. For handmade custom knives which are made from very hard, tough metals, you must bear down very hard in the initial stages in order to remove metal. There is a rhythm to this, and a lot more work than you might think. You'll see movie images of some chef whipping up an edge on a steel, and this is not how a fine knife is sharpened; it is how cheap (and soft) chef's knives are sharpened.

With fine, hard, blade steel, it takes a lot of work and careful attention to hone up a fine, razor-keen edge in several defined steps. You'll need a way to remove some serious metal: a coarse diamond stone, a coarse silicon carbide stone, or a slow speed wet grinder will do the job. Bear down hard, but not hard enough to bend or distort the blade or overheat it. A bright light helps. Keep the relief face angle as low as possible, without touching the spine or flat of the knife on the stone, or you'll scour the blade finish. Once completely relieved, you'll see or feel a burr of metal hanging on the edge. Now, you increase the angle by a few degrees by lifting the spine of the knife a small amount, and carefully start to sharpen. I like to use a hard Arkansas stone or hard, smooth ceramic stone for the final edge, and this is always done by hand.

The knife is pushed at an angle into the stone, and there is a definite rhythm. Control is the key here, you do not want to lift the spine of the knife and change the angle, or your work creating the relief face will be ruined.

Here are some pictures detailing the hand-sharpening of a hefty kukri. The instructions are the exact method I used to sharpen and maintain sharpness on every single knife. Note that the stone (this one is ceramic) is clamped in a vise for rigidity. You must have control of the sharpening process, and that means the stone must not move. Sometimes special benches are constructed with pockets to hold the stone and stop it from moving. But access to the stone at an elevated height works best for me, as the curvature of the blade may force me to have a hand below the level of the stone face. The steps:

• Grind enough of the relief face away to feel a burr on each side of the edge.
• Start defining the cutting edge with 10 strokes on one side, bearing down, then 10 strokes on the other side. All strokes start at the choil, and extend to the tip.
• 9 strokes one side, 9 strokes other side, bearing down
• 8 strokes one side, 8 strokes other side, bearing down
• 7 strokes one side, 7 strokes other side, bearing down
• 6 strokes one side, 6 strokes other side, bearing down
• 5 strokes one side, 5 strokes other side, bearing down
• 4 strokes one side, 4 strokes other side, bearing down
• 3 strokes one side, 3 strokes other side, bearing down
• 2 strokes one side, 2 strokes other side, bearing down
• 1 stroke one side, 1 stroke other side, bearing down (repeat this step ten times, decreasing the pressure on the stone each time until it's merely the weight of the blade)

The knife should be sharp enough now to glide through a single sheet of newspaper without sawing.

How do I sharpen the inside curve of a khukri or recurve blade?

Sharpening the inside curve of a khukri (kukri, khukuri), recurve, or concave profile knife is not easy. You might be tempted to use the corner of the stone, but don't! The pressure and surface area of that part of the stone will dig into the blade, and gouge the steel, creating a wavy, irregular edge. You must use a round ceramic or steel. I recommend the largest diameter ceramic you can find. This will be hard to find, because these are not commonly on the market. Factories don't really know what you need to maintain a sharp cutting edge, because they don't even send the knife from the factory with a sharp edge. The sharpening market is full of gadgets, tools and devices, but very few of them are actually needed. I use a coarse stone, a fine hard stone, and a round ceramic for inside curves and recurved blades.

The round ceramic is used just like a stone, with the same angles for the relief face and cutting edge face. The knife is dragged across the ceramic, or the ceramic is drawn across the knife. you can see the metal streaks on the ceramic, and this shows that metal is being removed. The sequence is the same as the standard sharpening sequence detailed above. Here are some pics that show a 1.25" ceramic tube being used to put a final edge on the inside (concave) curve of a Khukri.

What if I need more detailed information on sharpening knives?

Are there different degrees of sharpness? Of course there are. A scalpel has a completely different geometry than an axe, and the edge on a skinning knife is different than a combat tactical knife. A balance must be made between durability, longevity, and serviceability.

When I got into knives, I looked for the ultimate resource on the cutting edge. What I found was a man who had made a living for over 45 years as a sharpening consultant to the textile and meat packing industry. In industry, these guys don’t screw around. They don’t have time for confusing and mystical gimmicks or hyperbole. They must have the sharpest cutting edges, for the longest time, with a sharpening technique that is clear, maintainable, and very keen and effective. If you’ve ever seen the line at a packing plant, it is an amazing thing- the people are whipping meat off the bone at an incredible pace, and there is a reason they wear cut-resistant Kevlar gloves with wire reinforcement! In textile plants, razor sharp wheels, shears, and blades cut through thousands of miles of materials, textiles, and plastics, without snagging or tearing. This guy advised them on how to maintain their cutting edges.

His name was John Juranitch, and he wrote a good, short, concise book on what he knew. It’s called Razor Edge Sharpening and it’s available on the Razor Edge Sharpening website (at this link). This book is an absolute must have for every person who has ever or will ever sharpen a knife, and if you are reading this, you need to get this book. It blows away a heap of wives tales, myths, superstition, sales hype, misconceptions and outright lies about what it takes to create and maintain a sharp cutting edge on knives, axes, broadheads, and even fish hooks.

I have no personal or professional association or relationship with the owners of this site, but I do have a lot of respect for Juranitch's work and his no-nonsense writing style.

On the site, they also sell gadgets that help you maintain that sharpening angle, but I don’t recommend them on a custom knife, because they clamp on to the spine of the knife and can mar the finish. But the book resource is worth it, and that’s why I recommend Juranitch's book on every knife care sheet I supply with every knife. I can’t live long enough to have the experience this man has had sharpening blades, so I recommend what he learned.

What about sharpening or honing using steels or point contact, V-type, pinch type, or rod sharpeners?

First, hones and steels: I do not recommend any steel hones for sharpening. First, steels do not sharpen, they merely hone an already established edge, and if the blade steel is good steel, the edge shouldn't need honed. See the details of steeling in Juranitch's book, recommended in the previous topic and available (at this link).

Honing is usually needed on softer and cheaper steel blades (chef's production factory knives), because the edge rolls to one side or the other (on a microscopic level), or can become irregular. Steeling is recommended only for highly trained and skilled chefs, and with very light, surgeon-like, slow control because of the potential to damage a good, established cutting edge. And it is never used on a fine custom or handmade knife, because the edge does not need to be dressed like cheaper knives. Use only a fine, hard ceramic or Arkansas stone to maintain a fine razor keen edge on the knife after proper relief. It's funny how over the thousands of years of metal blades, a hard rock (whether it be ceramic, natural, or diamond) is still the best way to keep a fine cutting edge.

Second, rods and gizmos: About rods and pinch style sharpening hones: there is a bad price to pay for point-contact sharpening of any kind. There are many types of these sharpeners, called mouse trap, m-sharpeners, v-hones, power hones, steel guides, triangular sticks, guide rods, and many others. I do not recommend any of them because the blade only contacts the cutting edge on one small point (where the steel or hone is), it can cut or abrade the edge away unevenly. By applying more force in this one tiny area, and no control spread out over a long surface of the cutting edge, eventually the edge will wear away unevenly, leading to a wavy edge. For proper sharpening geometry, you can visualize how uniform and even a cutting edge will be if the knife is drawn across a two-inch wide ceramic stone, with a lot of surface area to spread out the pressure while pushing the knife against the stone. A point contact device would be like trying to sharpen the knife on the corner of the stone; no matter the guidance establishing an angle, the high force in a tiny area of the blade will eventually create a wavy blade! A wide sharpening stone will preserve the edge along the length and keep it even. The only exception is the inside curve, where you need a wide, round stone as listed above.

What is stropping and why is it done?

Most of us have seen a father, grandfather, or barber drag or whip a razor on a leather strop. Sometimes, these actions are so ingrained in our visual imagery of the knife that we associate the action with the profession and the connection between the two are anchored in media representations. If you see a man in a white smock whipping a straight razor across a wide leather belt, you automatically recognize him as a barber. But what is stropping and why is it done?

Stropping is done to polish the cutting edge of a knife blade. Since very little abrasion occurs in stropping, it doesn’t really create or hone the cutting edge in an aggressive way. The edge, having already been ground and honed, may have roughness due to the coarseness of the stone used to put the edge on the knife. A hard Arkansas stone, for instance, is a very fine abrasive, but it does have some tooth and that roughness can be felt along the cutting edge. Stropping was usually done by barbers, prior to shaving a client because they want the edge slick and smooth, so that it glides through the hair without snagging it and pulling or tugging just before the cut

Stropping a knife blade is not necessary in most cutting chores, as it does little to refine an edge. Improper stropping can actually damage a cutting edge, because if the angle is not just right, it will round over the cutting edge, making it less specific, and creating a convex profile that can only be corrected by re-grinding and re-sharpening. So, stropping a cutting edge should only be done by well-practiced professionals.

You can read all the details about just what constitutes a fine cutting edge in John Juranitch's book (at this link). It’s a good, professional text, and worth every penny.

What about hardness?

I always laugh when someone sends me a link to a factory knife page, where it's stated that they use a highly guarded secret process to heat treat their knife steel. Usually this is followed by a description of the steel in vague terms, and how it's special only to their company, and they alone can offer the benefits of this special steel, and secret, magical process for heat treating. They try to apply so much mystique to what happens to the knife before you get it, that you don't notice the poor grind geometry, the thin, weak blade or the thick, unsharpenable blade, and the lousy handle bolsters, guards, fittings and sheath. This infuriates me, and I see it time and time and time again.

Hardening and tempering are not closely guarded proprietary secrets. They are clearly defined by the steel manufacturer for the type of steel and the intended use. There is no mystery or drama to the heat treating process, just good, clean practice. See some interesting tales about heat treating on my FAQ page at this bookmark.

Heat treating is how I got started making knives. I was working as an industrial electrician, and was talking to some welders about steel. It fascinated me that you could take a piece of steel, heat it and cool it in a certain fashion, and derive a piece that was dozens of times harder or softer than the original. They said, "If you want to learn about heat treating, make a knife."

So I did. That was in the late 70's. I made knives out of found steel, tungsten saw blades, leaf springs, old tools, files, and planer blades. I used torches and my eye to determine temperature, quenched in olive oil, motor oil, and brine. I used magnets to determine critical temps, and my eye to judge tempering colors. I tested with files for hardness, other knife blades for wear resistance, and a vise and a pipe to break the blades for grain inspection.

I modified and built my own host of ovens. I beefed up burnout ovens and added nitrogen diffusion inlets with high purity nitrogen applied through flow rate regulators and constructed multi-chamber ovens with independent, low gas circulating, inert gas quenching chambers. I added specialized electric elements and converted my ovens to rapid ramp, with some gaining 500°F when empty. These are hot, fast, and clean ovens. I modified special freezers for sub-zero quenching, and trained, learned, and trained some more, but the process is still the same. After profiling, the master grinds, the profile finishing, the filework, the engraving, the holes are drilled, all milling is completed and excess material is removed from the blade, the knife blade is heat treated. It's heated to a stress-relieving pre-soak, brought to its critical temperature, quenched to its maximum hardness, then tempered to the correct balance of hardness and temper for its intended use. The exact process is usually defined by the steel manufacturer. After hardening and tempering, the blade is finish ground.

But this is not the whole story. How a knife is heat treated and the final temper is critical in the creation of a knife. A knife must be as hard as possible for a long wearing edge, yet tough and resilient so the edge doesn't chip or the blade doesn't break. It's easy to understand then, why tempering is in many ways so much more important than setting the initial hardness.

What is the correct temper? It depends on the blade material, the cross sectional thickness, the type of knife, and its intended use. Most heat treaters set the blade at one temper: 58 Hardness on the Rockwell C scale (HRC). I have blades that range from 54 Rockwell C for heavy choppers that must be shock resistant and tough to 55HRC for springy, flexible fillet knives, to 56HRC for very thin ground moderate light trailing point blades, to 57HRC for standard but thinly ground knives with a light cross-sectional profile, to 58HRC for many standard knives, to 59HRC for harder, thicker tactical models, to 60HRC for short and robust small folders and heavy-spine knives, to 61HRC for special purpose cut off blades for hazardous materials rescue and light metal cutting. I even have blades that are differentially heat treated and tempered, for a range of hardnesses and temper along the blade! Where I set the final temper depends on three things: the manufacturers type of steel and his recommendations, the geometry of the grind and the cross-sectional area, and the client's intended final use. I can't see an outside heat-treater working with a hundred custom knife blades all from different makers knowing these details.

Read more about heat treating on my FAQ page here.

Just what is the Rockwell Hardness Scale, anyway?

In a crude way, beginning knifemakers and hobbyists can use a file or saw blade and tempering colors to judge their blade hardness. But after years of knife making, I've found these methods are not only guesses, they can be outright false, leading to poor blade performance, short blade life, or worse, a brittle blade that snaps and can cause a nasty accident.

There are several recognized methods to test metals for hardness, and thus durability. Since heat treating can produce a range of hardnesses on metals, each type of testing and each scale on those types are assigned by scientists' and machinists' reference sources for particular metals, uses, and alloys. Some of the major testing devices, tests, and scales are: Brinell, Rockwell, Shores Scleroscope, Vickers, Knoop, Monotron, and Keeps. We are concerned with only the Rockwell hardness test. The hardness tester is a machine that measures hardness by determining the depth of a penetration, and the penetration device and measurement scale we used is specific for tool steels, medium and high carbon tool steels and alloys. It is the "C" scale of the machine, so you will see the hardness referred to as "58C on the Rockwell scale," or "Rc58," or "58HRC." The penetrator used for knives in this device is a diamond point, though different penetrators in differing devices and materials may be used. Note in the picture in the previous picture just above, I'm using a portable tester: a tungsten carbide regulated spring punch as the penetrator, and a hand-held microscope micrometer to measure the penetration and thus, the hardness.

Mostly, in the studio now, I use the hardness tester pictured to the right. How the device works: The blade is placed on the anvil, and tension is adjusted to relieve play. A 10kg load is first applied, which causes initial penetration. The major load is applied (in the case of a diamond penetrator, I use a 150 kg load), and penetration occurs. Then, the major load is removed, with the minor load still applied, and the penetration is measured. This gives us an accurate reading of the exact hardness at the point of penetration, and thus the relative hardness and temper of the whole blade. The testing mark is usually placed where it won't be seen, since the mark is permanent in the blade.

Though the hardness tester is a fairly common sight in complete machine shops, it is sometimes neglected. This is a fine instrument, capable of very accurate readings when properly maintained and used. For example, a slight deviation of the penetrator by the compression of a dust in the bearing surfaces of the anvil that leads to one millionth of an inch displacement can cause significant deviation of the final reading, and give inaccurate results. This is a delicate instrument and has to be regularly cleaned, calibrated, and maintained.

General Hardness Table

To get a rough idea of hardness relative to other objects and tools, here is a general guide for comparison, based on high carbon alloy tool steels

Remember, this is only a rough guideline. Tool steels and alloy metals all differ, and there is no reason that a knife blade cannot be 60HRC in hardness, if the alloy will support the blade and still be tough (not brittle), and given the cross sectional thickness of the blade will support the intended use. Conversely, there is no reason a knife blade used for heavy chopping might be set at Rc55HRC, for added toughness and more resistance to chipping. It's about the alloy, the geometry, and the intended use.

Sometimes, I'll set a differing temper on one blade. I've used spine tempering, differential temper, and graduated temper methods where there are a group of differing hardnesses in the blade structure, for different effects. For example, a long, slender sword blade like a rapier might be tough and springy at the tip (55HRC), harder and more resistant to flexion in the center (57HRC), and very hard and durable at the ricasso, the thickest part that supports the handle and tang (60HRC). As makers, we are responsible for our decision and methods of heat treating and tempering, and thus, can set the specific hardness, toughness, and temper of the blade. With a properly equipped shop, experience, and knowledge of our alloys and blade construction, we can provide specific and exact performance standards.

What about blade finish?

I read some interesting views on blade finish on a popular knife bulletin board. Knife makers were talking amongst themselves, discussing the pros and cons of having a hand-rubbed finish on a knife blade. It's funny how the justifications become reasons, how tradition is ignored in the face of what some would call outright ignorance.

From my upcoming book:

Like this excerpt from my upcoming book? Email me here and let me know! Thanks!

Blade finishes are simply the way the surface of the steel is handled. Here's how they break down:

• The Satin Finish (or brushed finish): The simplest finish is to leave the grind marks on at about 240 grit. Sometimes, this is requested by clients who are going to scratch, rip, and scar the blade, and do not want to pay for the effort to finish a blade that's going to be marked up anyway. Some steels, like D2, S30V, 440V and S90V can not be effectively mirror finished, so satin finish is fine. It's the least expensive finish I do.
• The Bead Blasted Finish: This is accomplished by first grinding to 240 grit on the grinds and flats, then glass bead or sand blasting to uniformly rough the surface. This looks great on tactical, combat, or fighting knives where reflection of a shiny blade is unwanted. It also compliments a knife blade that will then be hot blued, for a completely flat black finish. The only drawback is that the texture of the steel surface tends to hold water and debris, and can accelerate corrosion if not cared for. A good property of the bead blasted blade is that it will hold or grip a heavy wax, so that if the blade is waxed regularly, corrosion is kept to a minimum. A satin, sanded, or mirror finished blade does not have as much tooth to hold the wax for a prolonged time. Some steels can not be mirror finished, so this finish applies to them too (see satin finish above)
• The Sanded Finish (also called hand-rubbed): This is very popular among knifemakers, but I seldom do it, and then only by request. Most makers hand-sand blades along their length, and their reasons vary. I've heard that "my buyers expect a sanded blade" and "my sanding is perfectly aligned with the knife" and "I sand to 1200 grit and you can look at my sanding with a microscope and it's perfect." Hmmm. I personally feel that most makers who sand cannot achieve a fine mirror polish, or are not willing to invest the time and effort into a proper high mirror finish. Simply, it's a short, quick way to finish a blade. I'm sure I'll get some angry mail over this comment, but history will bear me out. The finest blades were always mirror finished to the highest degree possible.
• A Mirror Finish is best, for a host of reasons. It's beautiful. High chromium and alloy tool steels can be made to obtain a gorgeous finish, even D2 with its characteristic orange peel appearance is enhanced by mirror finishing. A mirror finished blued blade is stunning. The mirror finish has the highest appeal among most collectors and users. It increases the value of the knife, also the cost as the blade labor is more than doubled (that's probably why most makers just sand their blades). Historically, the mirror finish is found on only the highest valued jewelry, firearms, blades, swords, and armament. A mirror finish doesn't hold debris, water, or corrosives. The blade slides through materials with less effort. And there are some studies that indicate a high polish increases the break resistance of the blade, because all fractures start from a surface imperfection.

What constitutes a good finish? Finishing of the blade must be uniform. The grind lines must be preserved, that is clearly and crisply defined on the face of the bade. There must be no waves, gouges, or scratches in the steel that is not part of the design. The grinds must not be washed over, that is: made slightly convex and beaten down by too much time spent on the buffer. Many makers do this, trying to buff away errors in the finish by spending a good 30 minutes on the aggressive buffing wheel.

How I mirror polish is: grind through 10 steps of grinding belts, from 36 grit to 2000 grit, then about two minutes on the buffer cleans up the fogginess and clarifies the finish. The grind lines remain crisp, the value is greater, the look is stunning. I'm known for some of the cleanest grinds in the business, a reputation well earned by years of sweat equity. I'll put my mirror finishes against any other knifemaker's in the world.

Is there a non-scratch blade?

Often, guys will write insisting on a blade that holds its finish, without scratching. There is an answer for them: it's the collector's knife, a knife that sits in a dust-free display cabinet, separate from its sheath, and never gets handled. The truth is, there is no such thing as a knife blade or sheath arrangement that will not scratch the finish of a blade, if the blade is ever used. A working knife will be inserted and withdrawn a thousand times from its sheath, and if just one speck of sand, dirt, or debris makes its way into the sheath, it will lead to a scratch or group of scratches, scuffs, and scars on the fine metalwork. See the related topic on my Handles Page. This is one of the reasons that some makers sand the knives along their length, to hide the natural wear marks within a pattern of sanding: applicable for low end utility knives, and it's a matter of preference.

Scratches on metal knife blades are the same as the scratches on a firearm that is withdrawn and inserted into its holster. Men have tried for centuries to limit this. Here are some of their attempts:

• Lining the sheaths with soft materials. Those materials will eventually separate from the sheath body and can actually attract and hold debris
• Constructing sheaths from soft materials. Bad idea, because not only can those materials hold contaminates and debris, but they may flex, allowing the blade to poke through... ouch!
• Leaving gap or play in the sheath for limited blade contact. Also not good, as the knife rattles in a loose sheath, and can fall out.
• Making knife components out of harder materials. This is a good thing for gemstone handles, as little scratches them, but no blade or fitting material can withstand sand, dirt, or contaminates completely. Sand is made of quartz, which is as hard as any knife blade, so will scratch it.
• Constant polishing. I know of makers who bring small buffers to their hotel rooms at shows to clean up their knives for sale. No client or knife user is going to bother with this.
• Lubricating with oils, waxes, and coatings. This won't help. In the case of oils, they will actually attract and hold debris, and might soften cements, materials, and adhesives in the sheath or knife. Waxes are fine, but their effects are limited. Painting or coating a blade is a cheap finishing process that should never be done on any knife. See my reasons at the next topic below.

Want to preserve your knife forever? I recommend a coat of Cosmolene® on the blade, wrap the knife in wax paper, and store it in a temperature and humidity controlled safe. It will be the ultimate "safe queen," and the envy of your working knives, tools, firearms, and the rest of your active life. Or you could just sand the blade along its length with 220 grit silicon carbide paper, and it will look like every other piece of cheap knife work out there... I'm kidding, of course.

What to do?

If the knife is a collector's piece, and you are interested in maintaining its value, just like a fine firearm, you'll want to limit its use and exposure, even to its own sheath. Keep it clean and dry and occasionally waxed with a museum quality microcrystalline wax.

If it's a working knife, expect some scratches and abrasions from use. Do your best, within reason, to keep the knife clean and dry, wax it occasionally, and be proud that you can afford to use a well-made knife.

In either case, never store the knife long-term in any sheath! See my Care of your Custom Knife page for more details.

Care of the knife includes the handle. By the way, the most scratch resistant material is gemstone, here's a link to details about the handle, bolster and guard.

What about blued blades and coatings?

For the same reason that you don't paint a ladder, I do not coat blades, because that would hide any potential flaws, imperfections, or cracks, and any coating would eventually chip and peel. Coatings also have the potential to accelerate corrosion, because moisture, corrosive fluids, and debris may be trapped between the coating and the blade, and if the blade cannot breathe, dry out, and be cleaned, it will corrode. All fine tool steels (even high chromium stainless tool steels) can rust if stored in an enclosed environment (including the sheath) because there is no truly corrosion proof tool steel. Eventually, all coatings will become nicked or scratched or, at the very least, be exposed to an opening at the cutting edge. Coatings are typically the sign of a cheap factory knife, as it is a very fast and inexpensive way to finish the blade. Spray it, bake it, and out the door it goes. I talk about that more on my FAQ page.

I do, however, perform professional hot bluing on blades. Bluing is a process of oxidizing (rust is a form of oxidation, uncontrolled and irregular). Hot bluing (which is what I do) is a controlled, deep passive oxidation process whereby the steel is cleaned thoroughly, chemically and molecularly, then immersed in a superheated boiling solution of sodium nitrate and other proprietary salts for 40 minutes or longer. This oxidizes the first several thousandths of an inch of the steel surface, which is a very deep penetration. The bluing process is the same used on all fine firearms, that black dark deep patina that takes years to buff, scrape, or polish off. My process excels in penetration; where most firearms might be blued for 10-20 minutes, I start at 40 and blue for up to 60 minutes, giving the deepest blue possible. To give you an illustration, when I cut my makers mark into a blued blade using a diamond point engraver at 50 pounds per square inch, it takes three full passes to cut through the bluing to achieve a bright cut!

To sum, hot caustic bluing is a well-recognized, time-proven method of inhibiting corrosion (not eliminating it) on the surface of carbon steels. My own son (in the 101st Airborne) has carried a hot blued skeletonized knife in combat in Iraq. So did his squad. They're very happy with the performance. I've had many blued knives in the field of combat, in the hands of hunters, and in fine collections for years without complaint.

Here's an email from a client who carried a bead-blasted and hot-blued knife in combat:

Jay,

That Grim Reaper knife made it through two year long rotations to Iraq. It is well made and the heat, sandstorms, and all that chaos that Iraq could throw at it did not phase it one bit. Thank you.

Very Respectfully, R. M.

More about this knife

What about coatings like Titanium Nitride and others on the blade and edge?

People that work with machine tools soon realize that the new coatings, Titanium Nitride (TiN), Titanium Carbonitride (TiCN), Titanium Aluminum Oxide (TiAlN), Steam Oxide, and Chrome coating, each have beneficial applications in the machine trades. Since these coatings are so good, why aren't they on knife blades?

Most machine tool coatings are applied to high speed steels, cermets, or carbides, at the cutting faces that cut other metals. That's because they are expected to have great cutting loads (on other metals) at high surface feet per minute speeds. The coatings help lubricity, prevent galling, and increase wear resistance, usually at high temperatures. In a knife, these kind of stresses are never encountered. Exactly how many SFPM can a person move a knife blade anyway? And they're applied for metal to metal cutting, rarely encountered on a knife blade. These same high speed steels, cermets, and carbides are also very brittle at high hardness. Toughness is more important in a knife blade, as it is expected to encounter substantial shock loads with a small cross sectional area to back them up. Usually, machine tool cutters (mills, drills, inserts) have a lot of meat (thick body of metal) in their core to support these loads. We aren't offered that opportunity in a knife blade, which must remain thin for carry, use, and reasonable sharpening. And probably the most important argument is that the instant a knife blade is sharpened (and it will have to be sharpened), the coating is gone from the microscopic cutting edge, where you would need it in the first place.

Don't get me wrong, I love TiN and TiCN on my mills, HSS taps, cermet inserts and carbide tools for my lathes, drills, and mills. But on a knife it is a ridiculous gimmick, and an increased expense to clients. It's more important to have a proper selection of tool steel type for the application, proper grind geometry for the intended use, and proper heat treat of the blade steel in the process of making a fine, reliable, modern hand knife.

Serrations/Teeth?

Serrations or rip teeth are put on knives to tear through hard or other materials that are more effectively sawn than cut. Hard plastics, hard wood, some lines, bone, textiles, or synthetics may be more easily attacked by teeth than a fine blade. When I started making blades for the military, they requested serrations that work, unlike many found on factory knives. I believe that serrations must be sharp, at the points and in the hollows, and I use a diamond grinder to form, shape and sharpen them after heat treating. A couple things to consider about serrations:

• They subtract overall cutting edge length of the knife. If your knife has a 6" blade, perhaps a 5.5" cutting edge, and you decide on 2" of serrations, you're left with a 3.5" knife blade. On shorter blades, this is very noticeable.
• Serrations make a knife harder to insert and remove from a sheath. Careful design cannot always help, and you might find your sheath welts ripped up from the teeth over a period of time. Learn more about sheaths.
• Serrations may be hard to sharpen. They often are. I use special equipment (diamond abrasive based cutters) to make them and hone them, and that same equipment is not available in the field. Also, each type of tooth is different, and requires its own sharpening regime.
• The teeth may break off, because sharp teeth must be thin teeth. One of the military requirements I've had is to make a tooth that will keep cutting even after broken. This means a initial thinner cross section, and a more aggressive tooth.
• The serrations may hang up when you don't want them to. You may be using your regular cutting edge, and have material you're cutting fall into the serrated part of the blade, hanging up or snagging unexpectedly, and perhaps ripping up a clean cut or causing hesitation that is undesired.
• Because serrations require brute force to rip, they should be called rip teeth, and are usually placed near the ricasso, not at the end of the blade. That way, more force and the heavier cross sectional geometry of the blade will support their use. If serrations are put near the blade tip, it's possible that when they snag, the force of the hand with the leverage of the blade length may offer enough force to snap of the tip of the blade, the weakest part of every knife.
• All detriments noted, rip teeth when used should be very aggressive, not just a "steak knife" type of file cuts to decorate the blade. I've had very positive comments on my tactical and combat rip teeth and serrations. In the chef's field, I've had fantastic results with my hand-carved "theatre-curtain" type bread-cutting serrations.

Line Cutters, Gut Hooks?

Line cutters and gut hooks look similar; they're both deeply scalloped narrow grinds that create a cutting edge inside the profile of the blade. The gut hook is used to slice through the skin of a game animal (gutting) without piercing the internal organs (which can contaminate the meat). The line cutter is used to snag, trap, and slice small line and monofilament with one hand. Here's an email answer I gave to someone who thought the two looked similar:

Below is picture of "Flamesteed," a specialized CSAR knife with a line cutter.

What about millwork or holes in blades?

Millwork refers to any cuts on or through the blade that is done by milling, which includes drilling holes in blades, bolsters or handle areas of the knife. There are several reasons for this practice.

• Weight reduction and balance: to reduce mass in areas of the knife where the strength of the blade won't be compromised. If a knife design contains a large portion of particularly thick and heavy spine, the knife may be "blade heavy," and feel out of balance. Milling and drilling in this area removes material, and if machined correctly with proper stress reduction in heat treating, conserves strength in the spine. Example.
• Embellishment: sometimes weight reduction may work with a decorative motif, and often this motif may extend into other parts of the knife such as pin arrangement in the handle or filework and edgework. Sometimes the milling is followed by hand filework for a fully carved effect. Example.
• Attachment holes: Milling of slots and holes through bolsters and the blade allow for the attachment of rings, thongs, or lanyards for security and accessories. Example.
• Vacuum breakers: To break the vacuum (really surface tension) when cutting wet material like food, so that it won't stick to the blade. Example.
• Finger rings: Example. For extra security, usually in tactical or combat knives, an arrangement of one or more finger rings is milled in the handle. The edges are dressed for comfort, and sized for easy insertion and removal. The largest finger or thumb is usually well under one inch in diameter, so one inch seems to be a good, comfortable size. Knife users have mixed feelings about finger rings, as the rings could remove a finger if the blade was somehow ripped from the hand. My view is that in tactical knives you do not want the knife to leave the hand, period, and if it did, it might end up in the enemy's hand. I can see no circumstance other than having the knife blade trapped in heavy mechanical equipment where this might be a problem. And if you have to hang your weigh by the knife blade, things have gone to hell already, and perhaps you'd better hang on! I assume no liability for finger rings, after all, these are edged weapons and tools. See great examples on my Military Combat and Tactical knives page.
• Mechanical slots: These are necessary in mechanical knives such as folding knives, drop blades, and slip blades where the shape of the milling is designed into the blade arrangement for movement, locking, and accessory use. Example.
• Cannelures or Fullers: These are milled areas usually found in the spine of blades, particularly swords and long daggers. Their purpose is to remove excess weight from the blade while preserving strength. They are not "Blood Grooves" as most Americans call them. The milling makes an "I beam" type of cross section in the blade, which limits lateral flexion (the side to side bending of a flat blade) while reducing overall weight in heavy or long blades. Example.
• Sinister uses: In the days of old, milled cuts and drilled holes in the blade were used to hold poisons of the time, causing infections and suffering to those cut by the blades. I do not recommend this practice... ordinarily. Example.

I offer all milled options in a blade. If it can be done, I've got the skills and equipment to do it. Milled slots with fileworked edges, complex crosses, waving curved designs through the blade, carving, geometric arrangements, and precision attachment holes: all these are available. Since I am responsible for all stress relieving, heat treating, hardening, and tempering, I'll make sure the milled angles, corners, edges, and shapes do not cause stress risers in the tool steel.

What about damascus steels?

There are two types of steel referred to as "Damascus." Crucible steel of ancient Persia, and modern pattern welded steel.

The term "Damascus steel" these days refer to pattern welded damascus, not the damascus of the past, which was forged from a crucible of smelted ore. The crucible recipe was a closely guarded secret and those recipes of the past are long lost. There have been some attempts and progress in recreating the crucible or Wootz steel of those days, but I'm sure the quality of crucible steels in a dung furnace exposed to oxygen, contaminates, imprecise alloy elements and temperature fluctuation could not compare to industrially manufactured modern tool and die steels. If they really were super steels of legendary status, don't you think that every industry would want to make their cutting and production tools out of them? Don't you think the military industrial complex would be using them for helicopter transmission gears? No, there is no miracle steel, only good modern tool steels, proven for performance.

I get a lot of questions about damascus steels. Here's my email reply to a man who wanted the steel folded at least 200 times to make it "battle ready and razor sharp."

In modern pattern welded damascus steels, many layers of hard high carbon steels are welded to many layers of soft low carbon steels, the blade is forged, ground, and etched to reveal a striking pattern. When considering strength and wear resistance, though damascus steels are far better than they used to be, they are still considered inferior to homogenous, isotropic, uniform tool steels which are created in clean, laboratory grade environments. Remember that every layer you see in the steel constitutes two welds, and welds are potential sources of stress and breakage. This does not mean that pattern welded damascus is not usable, it can be made very well, but it is not the choice of users who demand hardness, toughness, wear resistance, and break resistance, like military, police, or professionals. Typically, pattern welded damascus steel blades are for knife collectors where appearance is the primary concern

I'll add that I do make many damascus blades, and they are quite beautiful. You can look through the hundreds of images on this website and see many fine damascus bladed knives. I'm currently not forging my own billets and bars as there are many who do a very fine job of that, and I use their steels and their guidance to make fine damascus blades. Damascus blades are expensive, some as much as $100 an inch before they're ever made into a blade! But for those who admire fine steelwork, pattern welded damascus is a valuable, beautiful alternative to a uniform homogenous blade. The investment value can be increased on a collector's knife by the use of pattern welded damascus, and they're continuing to hold their own on the investment knife market.

What about laminated or layered blades?

Layering and laminating of tool steels for knives is nothing new and even a few modern factories are using laminated steel blades, under the Japanese moniker of san mai, which simply means three layer. In Finland, Norway, and Sweden, this is a very old and traditional method of knife making. A hard, perhaps even brittle core of high carbon steel is laminated over with a lower carbon or sometimes stainless steel. This is supposed to make a hard cutting edge and a more flexible and tougher exterior. As the knife is sharpened, it is the inner core of steel that is exposed at the cutting edge.

Although it probably works well, I believe that this was a practice that was started in the past due to a poorer nature of tool steels available at that time. The combination of both hardness and toughness was probably not available in uniform steel, so this modification was applied. There are some drawbacks to the technology.

• The hard blade core can mean a very brittle cutting edge. No matter how the lamination is applied, the advantage is supposed to be that the core is left very hard and thus is wear resistant. So, obviously, the core is the layer that is exposed to the abrasive action and stresses of cutting. Although the outer laminations would be tough and less brittle, the actual microscopic cutting edge could be easily chipped if left very hard, above 59HRC for most steels. And since the edge on a sharp knife is ground thinly in order to be sharp, the hard core is exposed to the most mechanical stresses, all the while being thin and more brittle than the rest of the blade. In order for the core to not be brittle, it may be tempered back, and this defeats the entire purpose of the hard core, tough exterior idea.
• Welding knife blades of dissimilar metals causes some drift decarburization. This will allow the higher carbon in the core to migrate to the lower carbon areas and lead to less than uniform crystalline structure of the steel and less carbon where you need it, thus less iron carbide, thus, less hardenability. A blade steel with less carbon has less wear resistance, which is more important than the decreased hardenability.
• Welding also changes the alloy components and their arrangements in the crystalline structure, thus affecting the original structure of the steel. The affects of this are largely untested.
• If these blades were proven to perform superlatively, we’d see them used widely in modern period pieces and in modern industry, where the advantages of the steel would be demonstrably proven. We do not.
• There is added expense of the process if done by hand, but for manufacturers, it's often a way to offer better performance for a cheaper blade cost. This is because a .625" thick sheet of high carbon, high alloy tool steel is tremendously cheaper (less than one third the price) than the same steel that is .1875" or .250" thick. It may not seem like much to the individual maker who only constructs a couple dozen knives a year, but in manufacturing thousands of knives, this represents a tremendous cost savings. Bean counters like this method, as plate welding technology has dramatically improved over the last several decades. They can purchase a thin sheet of very good high alloy steel, plate weld it in a sandwich to lower carbon inexpensive steel, make the blade essentially thicker and more voluminous, and still have a hardened and tempered edge. It is not superior to the full thickness steel, only a cheaper way of getting there. Because the sandwich is softer, and doesn't work harden, it is more easily machined, milled, ground, and finished, cutting costs significantly. Could it be that the manufacture of san mai is simply a way to cheapen the cost of manufacturing while touting some unique and historic advantage?
• Any laminations, layering, or welding operations create stresses in the blade that can lead to unreliability. Though I’m sure most of these blades perform well, they were forge welded in the process, and thus are subject to all the limitations of all welded blades like stress risers, pockets, and inclusions. These cannot be seen, and just like in pattern welded Damascus steel, the level of trust in the knife is limited. I wouldn’t recommend one to the military or professionals for combat or tactical use.

With modern, high carbon, high chromium, homogenous, isotropic steels this combination of hardness, toughness, wear resistance, and corrosion resistance is well-satisfied and proven. This means a uniform blade structure of the highest tensile strength possible at uniform hardness and wear resistance throughout the blade. All surfaces are wear resistant, all of the steel is capable of holding a hard, tough, and sharp edge, throughout the life of the knife, even when the geometry is changed by repeated sharpening.

It’s my belief that this process of layering nowadays is an artifact of historically necessary methods to achieve a high quality blade with limited resources, and has evolved into a way of cost cutting in the method of modern manufacturing process.

With just about any steel manufacturing process, you have rabid supporters who are quick to jump to the defense of their particular favorite type of steel. Laminated steels have the same proponents, and from time to time I receive their overly enthusiastic emails proclaiming my opinion should be changed, and so should this very section on my website. That won't happen, but you may find some humor in the following:

One guy posted on a small knife bulletin board that the use of laminates was widespread in the woodworking world, such as in chisels. These argumentative types keep me on my toes, and I had to consider it (for about ten seconds). Tool steel laminate blades are used in specialty hand applications like chisels, and some hand planes because they can offer a cheaper version of a fine tool steel blade. If they were superior, you would see them used in powered planer blades and high speed corrosion resistant ball bearings, where real tools come into hard contact and high feeds and pressures with abrasive woods and metals at high temperatures. What do they make these cutting blades and bearings with? Solid D2, 440C, and 154CM, the equivalent of ATS-34.

Then, the guy mentions something about a catastrophic failure if a crack started in a hardened blade and the laminate would prevent it. What? First, if you're cracking a hardened blade at the edge, you need to go get another tool, not a knife. And if you do crack the cutting edge, the knife is ruined anyway, so go get another tool. If you're worried about a knife being up to the task, and figure it might break, Go get another tool! These arguments are ridiculous, and usually only meant to challenge, stir controversy, and draw attention to the writer. And if you're cracking a blade, it sounds like it's too brittle, and the brittle core of the laminated blade is at fault anyway!

Filework and Edgework

Filework probably started as a way to stop the thumb or fingers from slipping on a slick spine of a knife blade. It has evolved into a highly decorative art form, sometimes even embraced with engraving and precious metal inlays, differential anodizing, finishing, and bluing. The edge of the spine is its own canvas, and it seems every knife begs for its own style or pattern. The filework on one blade may take from one to eight hours to complete, each cut performed while bent over a filework vise with proper magnifier.

Filework and edgework personalizes a knife, is an absolute indicator that the knife is uniquely hand and custom made, and still functions to stop the hand or fingers from slipping on a slick spine. No factory knife will ever imitate fine filework. This particular skill, working on a curved surface down a tapered, narrowing tang can only be achieved by a skilled hand.

What to look for: Crisp clean design, not washed over by too much buffing. Regular, punctuated spacing, a nice design concept. Cuts on both sides matching. Depths of cuts matching. Advanced filework is graduated, that is, it gets smaller in size and spacing as the tapered tang gets smaller in width. Filework does not regularly extend deep into the grind at the tip, as this would weaken the tip of the point.

I keep a pattern book of my most favorite designs, and I offer three lengths of filework:

• Blade only: just the spine from the tip to the ricasso. Where the thumb or forefinger can get some purchase on the blade.
• Spine only: from the tip to the butt of the handle, top only
• Full: from the tip to the choil, all the way down the blade, around the tang, and ending in an often sculpted choil

Read more about filework, with some fine pictures on the Embellishment page.

I didn't get my answer here.

If you are interested in other topics about knives, swords, axes, daggers, or any other blades, let me know and I'll add a section!

And please remember this: