I. Knife Selection

Blade Material
Stainless steel resists corrosion and holds an edge better than high carbon steel. Although the name would imply otherwise, it will stain or discolor if left in adverse conditions long enough. The process of making “stainless” steel involves adding Chromium and reducing its Carbon content during the smelting process. As the chrome increases and the carbon decreases, the steel becomes more "stainless" but it also becomes more and more difficult to sharpen and, some authorities claim, the edge-holding potential is seriously impaired. We find that most stainless steel blades are as sharp as other material blades and hold an edge just as well as high carbon blades.

Blade Type
Most unserrated blades are designed to slice soft things like animal flesh, tape, food products or string, but would wear down quickly if used on hard or rough textured objects (like rope or webbing). For the latter objects, a partially serrated blade is a better choice.

The Grind
A quality blade may need sharpening only every 2 to 3 years. We suggest knives be professionally sharpened but if you do it yourself, use an India stone not a diamond hone. The diamond bone grinds too much of the edge down. Be sure to choose the grind style best suited for the tasks performed with the knife.

Other Factors
Handles, locks and grips: Be sure the handle is comfortable for you, the locking mechanism is strong and the grip is textured or rubber. For fixed-blade knives, make sure the blade extends well into the handle for improved strength and balance.

II. Blade Steels

AUS-8 (8A) - AUS 8A is a high carbon, low chromium stainless steel that has proven, over time, to be a very good compromise between toughness, strength, edge holding and resistance to corrosion.

ATS-34 - Premium grade of stainless steel used by most custom knifemakers and upper echelon factory knives. It is Japanese steel, owned by Hitachi Steels. The American made equivalent of ATS-34 is 154CM, a steel popularized by renowned maker Bob Loveless.

GIN-1 - Another low cost steel, but slightly softer than AUS-8. Formerly known as G2

CPM-T440V - Currently touted as the "super steel", it outlasts all stainless steels on the market today. It is, however, harder to resharpen (due to its unprecedented edge retention). But the tradeoff is that you do not have to sharpen as frequently. CPM-T440V is widely used by custom knife makers and is slowly finding its way into high-end factory knives.

SAN MAI III - An expensive, traditional style Japanese laminate. Hard, high carbon stainless forms the core and edge of the blade, while two layers of tough, spring tempered stainless support and strengthen it. The resulting blade possesses the best qualities of both types of steel.

This laminate is 25% stronger than the incredibly tough AUS 8A stainless . The telltale sign of genuine San Mai III is a thin line near the edge that runs the entire length of the blade. This line is created in the grinding process as the layers of steel in the blade are exposed. The distance the line is from the edge varies from knife to knife because every piece of San Mai III steel is unique.

Like AUS 8A stainless, San Mai III is treated in modern, precise conveyor furnaces and subjected to a sub zero post hardening process. This improves the microstructure of the steel by eliminating retained austenite. The resulting blades are more elastic and have better edge holding characteristics than standard stainless steels.

420J2 - Due to its low carbon high chromium content this steel is an excellent choice for making tough (bends instead of breaking), shock absorbing knife blades with excellent resistance to corrosion and moderate edge holding ability. It is an ideal candidate for knife blades that will be subject to a wide variety of environmental conditions including high temperature, humidity, and airborne corrosives such as salt in a marine environment. This extreme resistance to corrosion via its high chrome content also makes it a perfect choice for knife blades which are carried close to the body or in a pocket and blades which will receive little or no care or maintenance.

440C - A high-chromium stainless steel with great corrosion resistant properties. It is slightly softer than the 154CM. It is considered by many to be one of the finest blade materials available domestically. It takes and holds a keen edge with a minimal amount of effort and maintenance. Characteristics of this steel include extremely high corrosion resistance when compared to ATS-34 and some other "stainless steels," high wear resistance, and good cutting qualities. This fine stainless steel has lost some its "limelight" due to the popularity of ATS-34 in the past few years, but for wet or damp environments 440C is a superior choice.

0-1 - Is perhaps the most forgiving of any knife quality steel other than the very simple alloy types, and produces a blade of excellent quality for most normal use. It can be heat treated very easily. Edge holding is exceptional.

D-2 - Is another air hardening tool steel, but with 12% chrome and excellent, if not superb, wear resistance. A high carbon content steel for great abrasion resistance. The resistance also holds true in both sawing and grinding, even while the steel is fully annealed. D-2 anneals at somewhat higher temperature than A-2 and will not take a true, mirror polish. Definitely a steel for the advanced craftsman. Its major drawback is the orange peel appearance of the surface when finished to a high gloss. It is just below the stainless threshold so coating with BT2 adds corrosion resistance.

154CM - The American made equivalent of ATS-34. USA made by Crucible Steel. Developed for use in military jet engine turbine blades during the war. Due to its high carbon/chromium content it offers exceptional wear and resistance. For blade use, it offers super-fine grain structure which bodes well for excellent lasting edge sharpness.

BG-42 - The correct name for this steel is Lescalloyâ BG42â VIM-VAR. This is a high performance bearing steel made by Latrobe Steel Company in Latrobe, PA. A special manufacturing process combined with a very specific alloy results in a clean steel with good resistance to wear and corrosion. This type of steel is used for domestic, international and military aerospace applications. When compared with other types of steel, BG42 demonstrates superiority in areas of hardness, hot hardness, retention of hardness, corrosion resistance, oxidation resistance and wear resistance. The introduction of 1.2% Vanadium increases the steel’s toughness and edge retention.

Talonite - Talonite is a Cobalt Chromium alloy, a member of the Haynes Alloy family, that has been treated with a new hot rolling age hardening process. Talonite is the same composition as alloy 6BH (Stellite), except for the hot rolling and age hardening. The direct age hardening after hot rolling provides maximum hardness and wear resistance. The advantages this creates are increased wear resistance, increased hardness, and improved machining characteristics. Talonite is much easier to grind than other Stellite type alloys and has improved edge retention qualities.

CPM - A family of alloys with unique or enhanced properties that cannot be made by conventional steel manufacturing methods. In almost any application, CPM grades offer improved wear-resistance, toughness and grindability. CPM steels have no alloy segregation and exhibit extremely uniform carbide distribution. The types of vanadium CPMs found in many recent generations of knife blade steels include: 3V, 9V, 420V and 440V. Considered more "stiff" than ATS-34 or 154CM, but with longer edge holding properties and resistance to rust and staining.

A2 - A popular grade of cold work die tool steel. It has better wear resistance and toughness than O1 plus the dimensional stability offered by air hardening qualities. it's properties are more advantageous to certain types of knife making. More prone to rust and staining compared to "stainless steels".

S30V - A stainless steel created with the knife market in mind, alloyed to accommodate specific capabilities and manufactured to ensure clean, uniform steel. Unlike traditionally cast and rolled steels, S30V is made using the powder metallurgy process, a process that reduces molten alloy components to minute balls – or powder – which results in every grain comprising the exact composition of alloy elements. The powder is compressed under significant force to a homogenous, solid state and the steel is rolled to required stock size. Molecules are uniform, inclusions of impurities are insignificant and the development of large chrome carbides is a thing of the past.

M2 High-Speed Steel - A very tough, tool grade steel used as cutting steel and offering high abrasion/wear resistance. Offers high-impact strength with incredible edge holding properties. Non-stainless by nature, but Benchmade heat-treats before applying the BT2 coating to provide a high level of corrosion resistance.

Table 1.1 Steel Composition and Rockwell Constant Hardness Rating (HRC)

IV. Blade Grinds

Chisel Grind - The type of grind used in chisels. Where one side of the blade is totally flat, and only one side is ground at an "angle" or "bevel". Commonly found with "tanto" style blades, the chisel grind found popularity for tactical use. The philosophy being chisel ground blades were less difficult to sharpen on the field and were of a great thickness and there fore stronger.  

Comboedge - Refers to a partially serrated plain blade configuration. This serration pattern offers ideal cutting ability for fibrous materials such as webbing, straps, netting, and rope.

Concave Grind - Similar to the flat grind in that the blade tapers from the spine to the cutting edge, except the taper lines are arcs instead of straight lines.

Convex Grind - Similar to the flat grind in that the blade tapers from the spine to the cutting edge, except the taper lines are arcs extending outward instead of inward as in the convex grind above or straight lines. If you picture a pumpkin seed, you will get a good idea of what the cross sectional view of this grind is like. Noted custom knife maker Bill Moran is credited for bringing the convex grind into the focus of knife making.

Flat Grind - Flat grinds are characterized by the tapering of the blade from the spine down to the cutting edge. This style of grind is also referred to as a "V" grind, since the cross section of this grind resembles that letter. The chisel grind, a popular style for tactical blades, is a variation of the flat grind. On a chisel round blade, it is ground on one side, and on the other it is not. These blades are easier to sharpen, because you sharpen one side only.

Hollow Grind - The most common grind, found on the majority of custom and production pieces. Hollow ground blades have a thin edge that continues upwards, and is the grind is produced on both sides of the blade. Since the cutting edge is relatively thin, there is very little drag when cutting.

V. Coatings & Treatments 

BC1 Coating (Boron Carbide) - An extremely hard, thin ceramic coating applied in a vacuum chamber. Its extreme hardness and excellent adhesion provide wear resistance and lubricity while creating an attractive visual distinction in the process.

BT2 Coating - A Benchmade proprietary blade coating which is a black Teflon based polymer offering corrosion protection which exceeds the ASTM-117 specification for saltwater corrosion resistance. Due to its high lubricity, it helps make the knives operate more smoothly.

Heat-Treat - Heat-treating steels changes the structure of the material to make it stronger or weaker depending on the process used.

VII. Liner Materials

6AL-4V Titanium - A slightly lighter weight, modern metal offering incredible strength and resiliency. Key properties include non-magnetic and corrosion resistance.

410 Stainless Steel - An ideal 400 series steel offering good corrosion resistance and workability.

X. Serration Information

Patterns
Serrations on field knives are usually made up of two different sized scallops, two distinct patterns, and two distinct edge styles. Read on…

A typical serration pattern alternates two minor (smaller) points and one major (larger) point. There are, however; serration designs where the concave scallops are even – as those in bread knives or household steak knives.

A “standard” serration is one in which the major width of the minor scallop is concave (an "innie"). This serration style is found on the Gerber Gator Serrater, the Beretta AirLight Serrated, and Spyderco knives. A reverse serration is one in which the major width of the minor scallop is convex (an "outie"). This serration style is found on the Mission Knives MPK and most Benchmade knives.

Some believe that reverse serrations tend to work better when cutting wet line and materials filled with "gunk." The theory is that reverse serrations tend to be self-cleaning, in that the convex part of the scallop tends to push away the "gunk" that would normally clog the concave scallop.

Edge Styles
The two style of serrated edge are “radius” and “pointed”: radius being a smoother, curved serration and pointed being exactly as it sounds – pointed. We feel that radius edge serrations tend to cut easier than pointed serrations, but do not initially penetrate as easily. While a radius edge will glide through the material, a pointed edge will snag or dig into material being cut. This can be seen when cutting braided or woven materials such as nylon line, webbing, rope, or cord. A pointed edge serration will work best, however; when maximum penetration is required.

Miscellaneous Serration Info
Chisel serrations are now featured by a number of manufacturers. These serrations may be ground onto the blade with a small rotary tool, a chop saw/cut off saw wheel, or a chain saw file. The blade is usually sharpened first before the serrations are put on. This technique results in a sharpened blade edge between concave scallops. The benefit behind this design is two-fold: (a) the process can easily be done by a custom knife maker, and (b) the finished knife edge tends to "bounce" on the material being cut, thereby increasing the amount of applied force.

Laser serrations are another new technology often cleverly marketed as being “the most revolutionary knife making technology in the world”. Manufacturers claim these serrations keep their edge longer, or in some cases “forever”. While they would seem to hold their edge longer, it is only the "sawing" that allows the blade to remain functional even when it is quite dull. This in turn creates the illusion that the blade keeps it’s edge longer. In addition, the serrations effectively “lengthen” the total cutting edge which means for any given use, it will stay sharp longer - all other things being equal. The simple fact, however; is that all blades will dull eventually and the biggest problem with the laser serrated blade is that once dulled, it is impossible to sharpen. The only actions you can take when your laser blade gets dull is 1) grind the serrations off completely for a straight knife edge, or 2) return it to the company for a new one, depending on the manufacturer’s policy.

A Subjective Opinion on Serrated vs. Flat Blades
Serrated blades have their uses and strong points, but not as a primary wilderness blade, in my opinion. Stick to a plain edge for general use. Serrated blades do not lend themselves to many of the carving and chopping chores a knife may be used for. Their forte is slicing, or sawing or tearing, as the case may be. They are particularly good at slicing nylon and similar slick synthetic line, rope and webbed belts and harnesses, as well as clothes and flesh. In other words, they are great for paramedic or law enforcement use or as a defensive blade. They are an acceptable choice for marine survival use which is less demanding of a knife edge and where cutting lines and slicing open fish are the primary uses.

In the field, a person will cut whatever is needed, on any surface available. These "cutting boards" could be anything from the lid of a steel tool box, to the side of a pick-up truck bumper, or even a rock. The straight edge blade will soon become damaged under these harsh conditions, whereas, the serrated edge, with its protected inner edges, can sustain terrible damage and still cut.

A big down-side, however; is that serrated blades are much more difficult to sharpen in the field, though the right sharpener (round or tapered round, depending upon serration style) and practice will solve this problem. If you're caught out in the field without a knife sharpener, then you are out of luck. You can do a respectable job sharpening a plain edge blade using natural stone. You'll not have much success trying to do that with a serrated blade.

If you just cannot live without a serrated edge, look for a blade with something like a 70/30 or 60/40 split between the plain and serrated edge, with the plain edge forward of the serrated. Or, better yet, carry a separate serrated edge knife, or a knife with a separate serrated blade.

XI. The Truth Behind "Blood Grooves"

History of the K-bar
Owners of the USMC 1219C2, or “k-bar”, are probably aware of the term “blood groove” and are also probably under the impression that these serve some sort of purpose. We at Delta Gear take pride in dispelling the myths often created by clever marketing teams and therefore would like to give you a little history on the USMC 1219C2, the grooves-in-question (otherwise known as “fullers”) and how the term “blood groove” came into existence.

The first 1919C2 was created in the style of a commercial hunting knife that was produced by the Union Cutlery Company. And the Union Cutlery Company took their idea from a wildly successful “Ideal” hunting knife made by the Marbles Company. The Marbles knife had fullers that were quite wide and deep and were positioned lower on the blade. This ingenious design allowed the Marbles knife to be successfully flat-sharpened (by holding the blade flat) on a flat stone while in the field.

On comparing the Marbles knife to the USMC 1919C2 (or the Union Cutlery knife for that matter), one will immediately notice that the fullers on the latter two knives are much narrower, not as deep, and placed higher on the blade than those on the Marbles knife. These differences unfortunately negate the true purpose of the design and are rendered useless in terms of sharpening advantages. While the fullers on the Marbles served a valuable purpose in the field, it was completely lost to the designers who copied it.

Suction Theory
Once realized, the knock-off designers needed a justification for their blundered design which is how the “suction theory” and the term “blood grooves” came to be. In theory, these blood grooves help release the suction when withdrawing the knife from an animal or person. In this scenario, it is presumed that the victim’s muscles contract around the knife blade, creating a vacuum which makes the knife difficult to withdraw. Supposedly on a knife with a blood groove, blood can run through the grooves and break the suction, allowing the knife to be withdrawn more easily. One problem is that there is no proof that the muscles actually contract around a knife blade; and the second problem is that people testing knives with and without blood grooves say there is no noticeable difference. Experts agree that if your knife cuts its way in, it can cut its way out with or without “blood grooves.”

Now, taking that all into consideration let’s just return to the original term “fuller” from this point forward. It’s true that a fuller can serve a very important structural function, depending on the size of the blade. In swords, this design plays a far greater importance in terms of weight reduction. In a knife, however; the decreased weight is so small, it can be deemed insignificant. The strengthening properties of a fullered sword blade are also lost in knife design. Many believe the fuller plays a strictly decorative role on knives or swords under two feet long.

The bottom line is the term “blood groove” may sound cool but in fact is just a clever marketing scheme. Sorry folks, but that’s the story and we’re sticking to it.