Knife Blade Edges

Knife Blade Edges

The edge of a blade makes all the difference in how a knife handles and cuts. The right edge for the right job. Here is a list of different edge types and a few blade differences, too.

Clip Point

A clip point blade has a concave or straight cut-out at the tip (The "clip"). This brings the blade point lower for extra control and enhances the sharpness of the tip. You will often find a false edge with the clip point. These types of blades also often have an abundant belly for better slicing capabilities.

Dagger / Double Edge

A double edge blade is sharpened on both sides ending with the point aligned with the spine, in the middle of the blade.

Drop Point

The drop-point blade has lowered tip via a convex arc. This lowers the point for extra control and also leaves the strength. This type of blade also has a good-sized belly for better slicing.

Excell Edge

Technology uses ceramic Titanium Nitride coating to boost the edge hardness. The TiNi comes in a variety of colors.

Fusion Edge

The latest hard edge technology is where the blade is fused with tungsten carbide, a material four times harder than the hardest stainless steel allowing the edge to stay sharper 11,000 times longer than a traditional plain edged knife.

Granton Edge

Granton edges have semi-circular scallops ground into the edge that alternate on either side of the knife and extend from the edge to the middle of the blade. The design of scallop-sided blades is an attempt to ease the cutting and separation of meats, cheese, and vegetables. They are maintained just like regular edges.

Hollow Edge Blade

A hollow edge blade is a knife blade with a series of evenly spaced vertical indentations close to the cutting edge. These indentations confer several advantages to a hollow edge blade, making the blade very popular in busy kitchens. Many knives designed for sushi, such as santoku knives, are hollow edge blades. This type of knife blade should not be confused with a hollow ground blade.

Hook Blade

The edge of a hook blade curves in a concave manner.

Plain Edge

The plain edge is as it says and should have an angle of around 24 – 30 degrees. It will often require re-sharpening to maintain its fine edge.

Santuko Blade

Santuko is a Japanese Chef’s knife. The spine curves downward to meet the edge and the belly curves slightly.

Scalloped Edge

This edge uses the same peaks and troughs principle as the LASER serrated knives where the peaks provide the initial cut and protect the sharp troughs. This type of edge is most commonly found on bread knives.

Scimitar

This is a curved blade with the edge on the convex side.

Serrated Edge

Serrated blade knives have a wavy, scalloped or saw-like blade. Serrations make knives ideal for cutting things that are hard on the outside and soft on the inside (such as bread or tomatoes) that might otherwise be ruined by a slightly dull knife with a plain, flat-ground edge. They are also particularly good on fibrous foods like celery or cabbage. Serrated knives cut much better than plain edge blade knives when dull, so they may go longer without sharpening (some serrated blades are claimed never to need sharpening.) However, they require specialized equipment and a different technique in order to re-sharpen them.

Sheepsfoot

The spine of this blade curves downward to meet the edge. This leaves virtually no point. This type of blade typically has little or virtually no belly and is used mainly for slicing applications.

Spear Point

The point of this blade is exactly in the center of the blade and both edges are sharpened. The point drops all the way down the center of the blade.

Tanto

The point to this style blade is in line with the spine of the blade. This leaves the point thick and strong. There are quite a few different variations of how tanto blades are designed. The way the front edge meets the bottom edge, whether at an obtuse angle or a curve is one difference. You will also find differences in the point being clipped or not and whether there is a chisel grind.

Trailing Point

The trailing point blade’s point is higher than the spine. This is typically engineered with an extended belly for slicing, with the point up and out of the way.

Knife Blade Hardness

Blade Hardness

Blade hardness is yet another issue. Steels with more carbon will get harder on the Rockwell scale and steels with less will harden to a lesser degree. Harder steel will hold an edge longer, naturally, but will be more brittle (less tough) and harder to sharpen. Softer steel will be tougher and easier to sharpen but won’t hold an edge as well. Most modern high tech stainless steels are hardened to RC 58 to 60 which is a pretty good range for most cutlery applications.

The Basic Processes of Hardening Steel

The basic process of hardening steel by heat treatment consists of heating the metal to a temperature at which austenite is formed, usually about 760° to 870° C (about 1,400° to 1,600° F) and then cooling, or quenching, it rapidly in water or oil. Such hardening treatments, which form martensite, set up large internal strains in the metal, and these are relieved by tempering, or annealing, which consists of reheating the steel to a lower temperature.

Tempering results in a decrease in hardness and strength and an increase in ductility and toughness. The primary purpose of the heat-treating process is to control the amount, size, shape, and distribution of the cementite particles in the ferrite, which in turn determines the physical properties of the steel. Many variations of the basic process are practiced.

Time-Quenching

In time-quenching the steel is withdrawn from the quenching bath when it has reached the temperature at which the martensite begins to form, and is then cooled slowly in air.

Martempering

In martempering the steel is withdrawn from the quench at the same point, and is then placed in a constant-temperature bath until it attains a uniform temperature throughout its cross section. The steel is then allowed to cool in air through the temperature range of martensite formation, which for most steels is the range from about 288° C (about 550° F) to room temperature.

Austempering

In austempering the steel is quenched in a bath of metal or salt maintained at the constant temperature at which the desired structural change occurs and is held in this bath until the change is complete before being subjected to the final cooling.

Case Hardening

Any of several processes for hardening the surfaces of steel products in order to make them more resistant to abrasion and wear, while leaving the interior soft and therefore tougher and more fracture-resistant. The hardening may be accomplished by dissolving carbon into the surface, called carburizing, or by adding nitrogen, called cyaniding or nitriding.

Carburizing

In Carburizing, the piece is heated in charcoal or coke, or in carbonaceous gases such as methane or carbon monoxide.

Cyaniding

Cyaniding consists of hardening in a bath of molten cyanide salt to form both carbides and nitrides.

Nitriding

In Nitriding, steels of special composition are hardened by heating them in ammonia gas to form alloy nitrides.

Knife Blade Finish

Knife Blade Finish

There are several ways to finish a knife blade. The steel itself can be polished, satin finished or even bead blasted.

Bead Blast Finish

Bead blasting provides a textured gray finish to the steel. It is popular in tactical knives because it is less reflective. On the downside, bead blasting collects and holds moisture better than other finishes and, so, can allow the blade to rust more easily.

Coated Finish

Some blades are coated to provide moisture protection or even to improve blade performance.

Polished Finish

Polishing is attractive but expensive. It is a finish used more in the custom knife industry.

Satin Finish

Satin finish is less shiny since the blade has been ground but not polished. This is the least expensive of the popular finishes.

Teflon Coated Finish

Teflon is a popular blade coating which protects blades from corrosion forming moisture and which makes a blade less reflective. Many black blades are coated with Teflon.

Titanium Nitride Coated Finish

Titanium Nitride (TiNi) is an example of a very hard material that is used as a blade coating which can actually help the knife hold an edge better. TiNi is available in several colors.

Knife Blade Grinds

What is a Grind

The “grind” of a blade refers to the way in which it is finished for sharpening and eventual sale. Typically, a knife is only ground once, as the grinding process removes a great deal of metal. The knife will periodically need to be re-sharpened, and if it is particularly abused, it may need to be reground. Regrinding is only successful once or twice, as it eats away large portions of the blade.

Chisel Ground Blade

A chisel ground blade is a blade which is only sharpened on one side, creating a classical chisel-like shape in cross section. When a chisel ground blade is produced, one side of the blade is left totally flat, while the other is ground down to make a sharp wedge. One of the primary advantages of a chisel ground blade is that it tends to be extremely sharp, since the cutting edge of the blade has one angle, instead of two.

Edge Ground Blade

An edge ground blade is straight sided and an edge is ground directly onto it.

Flat Ground Blade

A flat ground blade is a knife blade which is evenly sharpened from the spine to the edge. In order to be considered a true flat ground blade, the knife must be entirely lacking in bevels. Typically, a flat ground blade is V-shaped in cross section, reflecting a grind which gets thinner towards the edge so that it will be a more effective cutting implement. Because a flat ground blade is not beveled or shaped, it is very easy to sharpen. They are heavier and tougher than a hollow ground knife.

Hollow Ground Blade

Hollow ground blades have concave, beveled edges that are ground starting midway down the blade, instead of at the spine. Hollow ground knife blades are manufactured with a process that fuses two separate pieces of metal together. After the pieces are fused, a beveled blade edge is created. Although these blades often have very sharp edges, the blade lacks the balance and longevity of a taper ground blade.

Taper Ground Blade

Taper ground knives are manufactured with a single sheet of metal and are ground so that they taper smoothly from the spine to the cutting edge. This type of blade can be found on knives that are used frequently. A taper ground blade gives the finest edge possible and the consistent tapering blade allows it to glide easily through food.

Knife Construction

Construction

Basically, there are 3 ways to make a kitchen knife. You can block it, forge it or sinter it. Knives can also be made through an extensive hammering and grinding process. These techniques are still practiced be master craftsmen creating some very fine custom cutlery pieces, however, they are not a cost effective manufacturing process.

Blocked Blades / Stamped Blades

Blocked Blades / Stamped Blades are cut to shape directly from cold rolled steel, heat-treated for strength, then ground, polished, and sharpened. Though they are not preferred by most professional chefs, several popular knife brands, such as Global, do use stamped and heat-treated blades in their premium knives. Stamped blades can often, but not always, be identified by the absence of a bolster.

Forged Blades

Forged Blades are made in an intricate, multi-step process, often by skilled manual labor. A chunk of solid or powdered steel alloy is heated to a high temperature, and pounded while hot to form it. The blade is then heated above critical temperature (which varies between alloys), quenched in an appropriate quenchant, and tempered to the desired hardness. After forging and heat treating, the blade is polished and sharpened. Forged blades are typically thicker and heavier than stamped blades, an advantage in some situations. Forged blades were superior to stamped blades in the past but with modern technology this is no longer the case.

Sintered Knives

Sintered Knives are made by fusing together the blade and tang or, sometimes, the blade, bolster and tang to make up a complete knife from the various parts. This is done as an economy measure in some cases since it is less expensive than forging. In other cases it allows for construction that would be impossible without it.

Knife manufacturing videos

No matter what material, all knives used to be made by hand, one at a time. These informative YouTube Videos show how much work is involved in knife making. This first one shows you automated knife making http://www.youtube.com/watch?v=2Q46pGg8edg

The next 4 are by Greenpete and they show you how to make a single bevel blade from an old metal file. Not only does Greenpete reuse old metal, he does it in the field with a wood fire and a 12 volt car battery (that could be charged useing photo-voltaiacs).

#1 http://www.youtube.com/watch?v=5ysKd1cswlo.

#2 http://www.youtube.com/watch?v=yIvyPxyVKQc&feature=related

#3 http://www.youtube.com/watch?v=0XGnc8mgEBE

#4 http://www.youtube.com/watch?v=JBcxo4ojmgo

This one demonstrates Damascuss steel making. http://www.youtube.com/watch?v=NgcdSk4QpyU&feature=related

Classifications of Steel

Carbon Steels

More than 90 percent of all steels are carbon steels. Machines, automobile bodies, most structural steel for buildings, ship hulls, bedsprings, and bobby pins are among the products made of carbon steels.

Alloy Steels

These steels have a specified composition, containing certain percentages of vanadium, molybdenum, or other elements, as well as larger amounts of manganese, silicon, and copper than do the regular carbon steels. Automobile gears and axles, roller skates, and carving knives are some of the many things that are made of alloy steels.

High-Strength Low-Alloy Steels

They cost less than the regular alloy steels because they contain only small amounts of the expensive alloying elements. Girders can be made thinner without sacrificing their strength, and additional space is left for offices and apartments.

Stainless Steels

Stainless steels contain chromium, nickel, and other alloying elements that keep them bright and rust resistant in spite of moisture or the action of corrosive acids and gases. In kitchens and in plants where food is prepared, handling equipment is often made of stainless steel because it does not taint the food and can be easily cleaned.

Tool Steels

They contain tungsten, molybdenum, and other alloying elements that give them extra strength, hardness, and resistance to wear. These steels are fabricated into many types of tools or into the cutting and shaping parts of power-driven machinery for various manufacturing operations.

Knife Blade Materials

Importance Of Knife Blade Material

The first consideration of any knife should be the blade, and the steel that it is forged from. After all, as a knife it will be expected to be able to cut, and if you buy a knife from us you will expect it to cut very well indeed.

420 Series Stainless Steel

Typically found on presentation, display knives, and some hunting knives. Sharpness is okay which justifies it's entry into the surgical grade category. Easy to sharpen

Boye Dendritic

Boye Dendritic is a cobalt alloy. These blades are completely rust-resistant and still perform well as knife blades although they are expensive. This type of material is often found in knives that are used in and around salt water.

Branded Stainless Steels

Good levels of sharpness with acceptable levels of edge retention, so it's a good job they're easy to sharpen. Hard compound steel found primarily on folding knives. Very tough and easy to sharpen

Carbon Steel

Carbon steel is an alloy of iron and carbon, often including other alloys such as vanadium and manganese. A typical carbon steel blade is very inexpensive, and can be very sharp, and hold its edge well. Carbon steel is normally easier to re-sharpen than most stainless steels, but is vulnerable to rust and stains. Some professional cooks, particularly those in Asia, are partial to carbon steel blades because of their reasonable cost, cutting power, and edge-holding ability; others find these advantages outweighed in the kitchen by the extra maintenance required, as these blades must be cleaned, dried, and lubricated after each use or they will rust. New carbon-steel knives may also impart a metallic or "iron" flavor to acidic foods, though over time, the steel acquires a dark patina of oxidation which acts to block this process. Some people find patina a charming sign of age, while others find it unsightly. Very sharp, great edge retention and easy to sharpen

Ceramic

Ceramic is not a steel at all, they are made of zirconium oxide and aluminum Although they are much more delicate than steel knives, they tend to hold their edge up to 10 times longer. These blades are so hard that they will maintain a sharp edge for months or years with no maintenance at all. Like titanium, they do not impart any taste to food and are immune to corrosion. On the other hand, although ceramic blades can be sharpened on silicon carbide sandpaper or many grinding wheels, it is difficult enough that they are usually professionally sharpened. Also, they are hard enough to cut through glaze on dinnerware so should not be used as tableware. Further, although they are hard, ceramic blades are also very brittle, and will chip if struck against hard objects, or even sharpened improperly. Ceramic blades should only be used on wood or plastic cutting boards. Ceramic blades must never be used to pry or lever foods or other materials apart, as they may snap.

Damascus Steel

Damascus steel blades today are generally pattern welded steel, which is made of layers of steel and iron which are welded together. Japanese katana are made with Damascus steel. It is a folded mix of two types of steel, either Carbon or Stainless and combines the properties of the two individual blades. Excellent edge retention, Very sharp edge, and easy to sharpen

Hard Compound Steels

Very hard compound steels offering reasonable sharpness, but excellent strength and edge retention. Perfect on survival type knives and often found on military collectables. Can be unusually expensive and will rust if not cared for. Very Tough, Excellent Edge Retention, Easy to Sharpen

High Carbon Stainless Steel

High Carbon Stainless Steel normally refers to higher-grade, stainless steel alloys with a certain amount of carbon. Knives made from high carbon stainless steel offer a combination of the best attributes of carbon steel and stainless steel blades. High carbon stainless steel blades do not discolor or stain, and maintain a sharp edge. Most of these 'high-carbon' stainless blades also feature higher quality alloys than less expensive stainless knives, often including amounts of molybdenum, vanadium, cobalt, and other components intended to increase strength, edge-holding, and cutting ability.

High Carbon Steel

High carbon steel is actually the best performer providing more toughness and the ability to take a very sharp edge with less overall effort. However, high carbon steel is not stain resistant. It can rust and will discolor from use. After much use, high carbon steel kitchen knife blades will actually become black. This discoloration is purely cosmetic and does not affect the performance of the knife in any way. An example of this kind of knife is the Sabatier Au Carbone.

Laminated Blades

Laminated blades attempt to use the best of multiple materials by creating a layered sandwich of different steel alloys (there are no laminated blades made of plastic or ceramic.) Such knives are a modern descendant of the ancient Japanese San Mai sword-making process. Frequently a harder, more brittle steel is sandwiched between two softer, tougher steel alloys, so that the blade combines the attributes, to some extent, of both metals. A laminated blade's edge can often be made harder than an ordinary stainless steel knife, in turn facilitating a more acute grind on the cutting blade (thereby increasing the knife's cutting abilities).

Pakistan Steel

Pakistan steel - no ideas what's in it - iron ? - and that's about it. Dreadful levels of sharpness, no edge retention to speak of, and once it's blunt you'll never get an edge on it again.

Plastic

Plastic blades are not very sharp at all. Their primary use is for cutting through vegetables such as lettuce without causing them to discolor. (A steel knife will cause the cut edges of lettuce to turn black.) Plastic knives can cut skin, especially wet skin, but will not penetrate far into flesh, a boon for cooks. They cannot scratch dinnerware or cutting boards. They can be re-sharpened, but they are cheap enough that they are regarded as semi-disposable. They cannot be made as sharp as metal or ceramic blades, but since they are typically serrated, they may perform adequately for their intended purpose.

Premium Grade Stainless Steels

Premium grade stainless steels have impressive edge retention, corrosion / rust resistant and quite pure in compound form. They are very sharp and easy to re-sharpen. Nice choice for top quality hunting knives.

Stainless Steel

Stainless steel replaces some of the carbon in the steel alloy with chromium to make it resistant to corrosion. These steel alloys normally produce a steel that is less stain resistant than typical cutlery stainless steels but also hold an edge for a longer period of use or provide additional toughness or other characteristics. There is a tradeoff. As stain resistance increases, the ability for the blade to hold an edge decreases. Conversely as stain resistance decreases, the overall performance of the blade increases. These steels are very popular with knife makers and provide a good balance between performance and price.

Stainless Supersteels

Stainless Supersteels have world class edge retention and sharpness. They are extremely corrosion resistant and very pure in compound form. Stainless supersteels can be tricky to re-sharpen due to blades toughness, but by no means impossible. Knives made from stainless supersteels are very forgiving, a joy to own and use.

Stellite

Stellite is closely related to Talonite. Knives made with stellite resist wear and corrosion. Stellite blades resist heat well, and do not oxidize easily in any condition.

Super-grade Stainless Steel

Super-grade stainless steel offers the edge retention and sharpness of old fashioned carbon steel without the corrosion tendencies. On the downside, it can be very difficult to sharpen.

Superstainless Damascus Steel

The new breed of blade - superstainless damascus steel is the best you can buy - irrespective of price. It's very rare, hard to get hold of and expensive too, but it still offers value for money and exclusivity as the edge performance is light-years ahead of regular steels.

Supersteel

Supersteel is the best of all World's: incredible sharpness and edge retention, with ease of sharpening and servicing too, very corrosion resistant. Supersteels are typically a folded mix of two types of stainless steels. Expensive, but worth the extra money if you can justify the expense

Surgical Grade Stainless Steels

The benchmark for many knives now, and used extensively by most manufacturers. Very good sharpness, edge retention is acceptable but the steel is easy to service and sharpen. Corrosion resistance is good.

Talonite

Talonite is made of a cobalt-chromium alloy that forms carbides, so it tests soft by most hardness tests even though it's very hard and wears extremely well. These blades are completely rust-resistant and still perform well as knife blades although they are expensive. This type of material is often found in knives that are used in and around salt water. Boye Dendritic is another example of a cobalt blade.

Timascus

Timascus is a new twist on Damascus steel. Timascus is a Damascus blade made with Titanium as the metal. These knife blades will closely resemble steel Damascus, and vary widely in color due to the particular alloy used. Knife blades of this material will hold a highly polished finish, which will be brightly colored; or they can have a pearly finish, which will show off the ripples in the metal nicely.

Titanium

Titanium is metal that is lighter, anti-magnetic, more wear resistant, and more flexible than steel, but also less hard and it will not take as sharp an edge. But carbides in the titanium alloy allow them to be heat-treated to a sufficient hardness. Titanium does not impart any flavor to food. It is typically expensive.

Zirconium Oxide

Zirconium Oxide is a very hard ceramic material that is also used in knife blades. Ceramic blades hold an edge longer than any other material and are completely corrosion resistant. The downside to these blades is that they are brittle and can snap or chip in use. They cannot be used for prying at all and are difficult to sharpen.