Historically, the earliest versions of handles were wood overlays. The classic folding knives, the Spanish Navajas and French Opinels, had handles made of walnut, beech, oak, and other commonly available woods.

Handles made of horn and bone, as the hardest, most durable and wear-resistant materials, were the most reliable in the period before the advent of plastic and composite materials. Deer horn, elk horn, ivory, mammoth tusk, buffalo horn, stabilized mammoth tooth, and walrus tusk were all used. All of these material options were usually used as spacers in the metal cheeks of the hilt.

Today, only a small number of manufacturers have an all-wood handle left. Nowadays, the handle of a folding knife is an opportunity for a manufacturer to realize high-tech ideas in a wide variety of variants.

Among the modern and most common materials for folding knife handles are:

Metal handles

Metal handles are made mostly of aircraft-grade aluminum, titanium and steel.

Aviation aluminum is a metal alloy in which the alloying elements are: copper (4.5%), magnesium (1.6%) and manganese (0.7%). In the knife industry, it is mainly used in the 6061 alloy variant (6061 T-6 Aluminum). This alloy is corrosion resistant, lightweight and strong enough for a knife used for urban carry and low loads.

Titanium is a lightweight and strong material with a silvery white color. Titanium is a completely non-magnetic material. Knives are often used in quite aggressive conditions and do not rust at all. Titanium is significantly lighter than steel. Handles made of titanium are well anodized and take any color. All these qualities make it one of the most sought-after materials for expensive, premium knives. But it also has a distinct disadvantage – softness and rapid wear when interacting with steel. This necessitates the use of a special steel pad, the so-called “dryer”, on knives with a titanium frame-lock. Without it, the titanium locks on the handle often jam in the open state, which makes it impossible to use the knife properly.

Steel – Knife handles either use the same steel as the blade (this applies to the cheapest knives), or use a significantly cheaper and softer steel than the blade. The most commonly used steel for knife handles is 420 J2 steel, which is used by most of the well-known American companies. The main quality of steel for handles is corrosion resistance.

Composite handles

Micarta (fiberglass textolite) is a composite material consisting of fabric (most often cotton, canvas or linen fabric, occasionally paper) and a special synthetic resin adhesive. Such a composite allows you to create a handle of any color, with a beautiful, most fanciful pattern. Mikarta does not absorb odors, does not allow water to pass through. However, it has a noticeable disadvantage – when cracked or chipped, it begins to chip out at the point of damage, the thread begins to delaminate and fall out of the structure.

Glass Fiberglass Textolite G10 is a composite material that contains fiberglass cloth and epoxy resins. The process of production of the material is soaking glass fiber in resins, after which the impregnated glass fiber is subjected to compression. The result is a material that performs well under adverse conditions. G10 is a strong and impact-resistant material, perfectly tolerates moisture and can be colored (including layer-by-layer). This fiberglass textolite looks very similar to micarta, but is characterized by increased resistance to fire and higher strength. The main disadvantage of G-10 is that the handle becomes slippery and uncontrollable in a wet or greasy hand.

Dymondwood (Dymondwood) is the name of a composite material (laminated plastic). Its main components are wood, which serves as a base and phenolic resin, which is impregnated with wood. In the domestic market there is an analog of laminated plastic, – “delta-wood”. In the manufacture of Dymondwood natural wood is thoroughly dried, after which the voids are filled with polymer, which is able to quickly harden. Thus, the wood turns into a plastic-like material that does not deform, is strong enough, does not interact with water and is aesthetically appealing. Such a handle is not subject to corrosion, does not absorb odor and is quite cheap in production. The main disadvantage of this material is its weight, it is approximately one and a half times the weight of the original wood.

PaperStone (PaperStone) is essentially an analog of Bakelite, which is a material that contains cardboard (or paper) and phenol-formaldehyde resin. Extremely tough material, capable of withstanding strong impacts, pressure, friction, etc. It is often made from secondary raw materials (waste paper). Its main disadvantage is a very simple appearance, visually cheapening the product. In addition, this material becomes as cold as a stone in the frost.

Carbon (Carbon fiber) is a fabric made of carbon threads. It is folded into several layers and then impregnated with epoxy resin and dyed. Carbon fiber is a beautiful and lightweight, yet strong material. Carbon is lighter but stronger than steel, it has excellent anti-corrosion characteristics, is chemically neutral and can withstand heavy loads. The main problem of carbon is the high harmfulness of the production of the handles themselves, as the processing of this material affects human respiratory tract. In addition, it fades in the sun and can break under impact loading. Nevertheless, today it is one of the main materials of expensive, premium knives.

Synthetic Rubber

Kraton is a synthetic rubber – a TPE (Thermoplastic Elastomer). Two companies’ elastomers are most commonly used in knife manufacturing. These are Santoprene (Santoprene) material from Advanced Elastomer Systems and Kraton, produced by Shell. Knife handles made of elastomers (Kraton in particular) are produced by high-pressure molding. These materials can be deformed quite easily, and afterwards they take the same volume and shape. A handle made of this material should stick to your hand slightly, which is one of the main signs of a good elastomer.

Elastron (Elastron G) is a polymerized butyl rubber. It is as strong as vulcanized rubber and remains flexible at temperatures from -65° to 150°C. It has good water repellency and resistance to chemical attack. The material withstands high loads and remains warm enough in cold weather. However, when damaged, it quickly deteriorates, falling off in irregular pieces.

Plastic

FRN Thermoplastic (Fiberglass Reinforced Nylon) is a fiberglass reinforced nylon. FRN thermoplastic withstands high temperature loads, has high impact strength, dielectric properties, is well colored, practically does not burn, has low moisture absorption and high chemical resistance, low weight. It is also quite cheap in production. The disadvantages of the material include high fragility in conditions of severe frost. Today it is one of the most common materials in the world’s largest manufacturers.

Today, due to the development of the knife industry and the expansion of the range of knife steels, sharpening knives on diamond stones has become a necessity. This is due to the fact that the vanadium content in modern knife steels often reaches up to 10%, and the tungsten content can exceed 10%. In addition, in modern powder steels the carbon content can approach 2.14%, formally placing such steels in the category of cast iron. Effective sharpening of such steels is possible only on diamond (or elboron) stones. Compared to conventional abrasives, diamond bar provides increased accuracy of tool and parts processing, as well as an increase in tool durability after diamond sharpening in 1.2 – 2.5 times, and most importantly a significant increase in the speed of work.

Diamond powders are the abrasive base of diamond stones. They consist of natural or synthetic diamonds and are divided into two groups: grinding powders and micropowders. Grinding powders are usually used in the manufacture of diamond tools, while micropowders are used for pastes and suspensions. In the Russian diamond industry, for organic bonded stones (intended for sharpening tools), two types of grinding powders are mainly used:

1) AC4. From synthetic diamonds, grains of which are represented by aggregates and aggregates.

2) AC6. Synthetic diamonds, the grains of which are represented by individual crystals with a developed surface, aggregates and intergrowths.

A high quality diamond bar has an inherently higher aggressiveness of cutting precisely because of the grains that protrude excessively above the working surface. In the course of work, these grains either break off or chip out of the bond, and after a short period of initial use, the stone reaches its nominal cut and should last a very long time in this condition.

The organic binder itself consists of phenol formaldehyde resins and various compositions based on them. During hot pressing, the compositions are bakelized into a hard and sufficiently strong substance that holds the cutting grains in the working layer of the tool. At the same time such a bond will be strong enough and ductile enough, but not stiff enough.

The concentration of diamond powder is an important factor in the effectiveness of such a bond. For AC4 and AC6 grinding powders, this concentration leaves 50% or 100%. It is the concentration of diamond in the powder that determines its cutting ability, performance, service life and cost. The choice of concentration depends on the type of tool, the shape and size of the working surface, the grain size of the diamond powder, the wear resistance of the bond, and the machining conditions. To prevent such a bond from being too soft and ineffective on materials with high hardness, additional abrasive grinding powders, such as boron carbide, are added to it.

However, for sharpening the cutting edge of a knife, the bond can be even softer than for a specialized tool without losing effectiveness. For this purpose, the most advanced technology, used, for example, in the production of the Venevsky Diamond Tool Factory, are bars on a new modernized OSB bond. It is based not on grinding powder, but on ACM micro powder made of synthetic diamonds of normal abrasiveness.

What makes OSB bonding different from others is that it does not use boron carbide. In addition, the abrasive layer on it is not sintered, but glued to the body of the metal plate. At the same time the concentration of diamonds in these bars is 100% and already out of the box they are ready to work and do not require leveling on silicon carbide powder. OSB is ideal for hard steels at small angles. You can work on this bond with both soapy water and oil. While the manufacturer himself recommends working with either water or soapy water, working with oil gives an excellent result in terms of cleanliness of the process itself, without leaving such a large amount of water slurry.

Japanese company Naniwa was founded in Osaka in 1941. Its main activity is the production of various sharpening products for cutting tools. Today, Naniwa has an excellent reputation as a manufacturer of high-quality classic water stones for sharpening and is the recognized world leader in the production of magnesia-bonded aluminum oxide abrasives. In addition to premium artificial abrasives, Naniwa also produces a variety of profile accessories such as stone holders and stands, sharpening stones, sharpening stones dressing stones, etc.

Naniwa sharpening stones are synthetic abrasives and are manufactured using the most advanced technology, with a variety of bonding agents. Due to the unique manufacturing technology, these stones are characterized by high performance and due to their structure can be used for any steel with a hardness of up to 68 Rockwell units. Compared to natural sharpening stones, they have a more homogeneous composition and produce much more suspension. The grain is constantly renewed during the sharpening process, resulting in a high performance gain.

Naniwa produces two of today’s most sought-after synthetic water stone series, Naniwa Professional Stones and Naniwa Super Stones, as well as several other specialized series.

Naniwa Professional Stones

The most popular series is the Naniwa Professional Stones or Naniwa Chosera series for the Japanese market. The size of the stone is 210x70x20. This is a series of high quality stones designed for professionals who are professionally engaged in sharpening cutting tools. This series is categorized as professional stones because of its very high productivity. It is this parameter is emphasized by the creators of the Professional Stone series.

The stones are made with a magnesia bond. It is a magnesia cement that hardens in air by mixing caustic magnesite and magnesium chloride solution. Magnesia-bonded abrasive has low mechanical strength and hygroscopicity, so it should be stored in a dry room. Moisture leads to cracking of the bars and their further unsuitability for sharpening work. One of the main features of this bond is its high density with a uniform consistency of finely dispersed abrasive particles. This gives the bars the highest work efficiency among water stones. The most popular stones from this series are:

1. Naniwa Professional Stone #600 series water stone is designed for deburring and rough sharpening.

2. Naniwa Professional Stone #1000 series water stone is for basic sharpening.

3. Naniwa Professional Stone #3000 series water stone is for basic sharpening.

4. Naniwa Professional Stone #5000 series water stone is for pre-finish sharpening.

There are also other stones in the Naniwa Professional series from 400 to 10000. The grit of all these stones is given in the Japanese JIS system.

Naniwa Super Stones

The Naniwa Sharpening Stones or Naniwa Super Stones series for the Japanese market, has the same sharpening bar sizes as the Naniwa Professional Stone series. It is designed for sharpening the widest range of cutting tools, both in terms of purpose and material of manufacture. Compared to the Naniwa Professional Stone Series, this series has a smaller capacity, but the stones are slower to produce. This series is made with an organic bond, with Bakelitized resin as a base. The stones themselves are more durable than Naniwa Professional, but remove metal less productively.

Naniwa also produces other series of stones: Naniwa Specialty Stones are multi-purpose stones for specialized tools. Naniwa (Traditional Stones) – designed to work specifically with Japanese knives and other cutting tools made with traditional technologies such as Shiro Gami (white paper), Ki Gami (yellow paper), Ao Gami (blue paper), etc.; Naniwa Coarse Stone – coarse stones for coarse deburring work, etc.

Naniwa stones, regardless of the series, do not require immersion in water, and a spray gun is required to work with them. These abrasives are sensitive to prolonged exposure to water. They should be dried well and stored in a dry place. If the storage rules are not followed, the stones may crack and lose their abrasive properties. They should not be left wet in the cold, frozen water can destroy the stone. These abrasives may have white salt streaks (efflorescence), which is normal. They should be allowed to air dry when finished. Do not try to speed up the drying process by exposing the bars to heat; they must dry evenly to retain their qualities. Stones that are completely dry can be put away for storage.

Naniwa abrasives need regular dressing to help reduce uneven wear. Stones should be dressed on the thickest possible glass with their own slurry, without silicon carbide powder.

Special stands can be used to make working with these stones more comfortable. They help to prevent the water stone from slipping and lift the stone off the work surface, which is especially useful when sharpening knives.

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Damascus steel is a composite carbon steel with a visible pattern that has been made by mankind for several millennia. One of the most common and at the same time the easiest to make types of such metal is the so-called “wild damask”. It is made by welding a package of strips from several grades of steel, with multiple bending and forging. The package is heated in a crucible and added on top of various materials (so-called flux), which fuses with the scale formed on the surface of the plates, cleans from it welded surfaces. Dissolving scale, flux simultaneously forms a liquid slag, protecting the surface of the metal from further oxidation. Package with liquid slag heated to white heat and forged. After the first welding of the package it is uncovered on a strip and cut into several pieces, which are again stacked and made a second welding. Welding can be repeated many times until the desired steel characteristics appear. As a result, the layers of metal are mixed randomly and a pattern is formed on the surface of the bar. The appearance of the pattern depends on the number of layers and the grades of steel used. Light lines in the steel pattern give a high level of chromium or nickel. Dark lines show the use of carbon steels.

There are a number of standard problems associated with creating damascus. The main quality of Damascus steel is considered to be the alternating layers of metal with high carbon content, which give an aggressive cut, and low carbon content, which give it strength. However, during forge welding of layers with different carbon content, carbon diffusion occurs and they mix with each other. This degrades the cutting properties of the high-carbon components of the package by depleting the amount of carbon, and the large number of welds can reduce the strength of the blade. Moreover, the amount of carbon can burn out to appreciable amounts during the welding process, weakening the wear resistance of the steel. As a result, the consumer cannot often predict the properties of the resulting blade. It is widely known that damask can for no apparent reason simply stop cutting even on a well-sharpened knife, it can flake out, become very brittle. The fight against these drawbacks and the development of powder steel production technologies pushed knife makers first to artisanal experiments with powder steels, and then to the application of complex high-tech solutions.

The key role in the development of modern damask manufacturing technologies was played by the appearance of new technological equipment in the knife industry. Industrial forging presses, electric arc furnaces with controlled atmosphere, etc. began to be used for manufacturing of knife steel. In particular, specialized vacuum rolling mills, expanded productivity and allowed the development of industrial production of damask on the basis of the latest technologies of powder metallurgy.

The use of vacuum technology for the production of Damascus steel, allows the use of both metal bars and powder method as raw materials.

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The main advantage of the vacuum method for welding plates of traditional damask is the absence of oxidation of metal during heating. This makes it possible to pre-weld high-alloyed, including stainless steels without flux. Connected ground plates are welded by diffusion welding in a vacuum chamber under a press. The package welded in this way is expanded into plates, which are again ground and welded until the required number of layers is obtained. This method can be used to produce damask from stainless and alloy steels. An excellent method of welding high-alloy steels is also rolling a package of ground or otherwise cleaned plates on a vacuum rolling mill.

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The vacuum method is also used in powder metallurgy. A sealed, oxygen-free capsule filled with wire, metal powder or mixtures is placed in an inert gas-filled chamber of a gas-stat. The capsule is heated to 1200-1400°C and the chamber is filled with gas, up to a pressure of approximately 1500 atmospheres. After the pressurized sintering of the composite material is complete, the sintered composite shell is mechanically removed and the cleaned composite is press forged or rolled through a rolling mill. Almost any type of damask can be produced by this method.

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The advent of these technologies made it possible for large steel companies to produce damask in very large quantities. The largest of these companies was the Swedish Damasteel AB, which in 1996 received a patent for the production of powdered damask blanks. Damasteel’s production technology was “hot isostatic pressing”, which turns a rapidly hardening powder into a compact billet. Powders of two or more types of steel are placed in the center of a steel capsule in which a vacuum is created and hermetically sealed. The powders are sintered together under high pressure in a hot isostatic press. Pressing continues until the density reaches 100%. Damasteel produces two types of billets by powder metallurgy – bars with a layered concentric pattern and a multilayer package with parallel layers. The billets can then be used to create more complex patterns in the forging process.

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The advantages of Damasteel steel are high corrosion resistance, predictable heat treatment regimes, pure chemical composition with minimal impurities, very good cutting properties when alloyed with vanadium. It is also important that the hardness of the metal after heat treatment reaches 63.5 HRC. With ordinary damask it is impossible to speak accurately about the hardness, it will be extremely heterogeneous throughout the blade after forging. Powdered damask solves this problem by creating a homogeneous structure. In addition to making knives, Damascus steel is also used to create a variety of jewelry and costume jewelry. Damasteel steel is also used to create items made with the Japanese mokume-gane technique.

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Damasteel is based on RWL34 steel, a powdered, high-carbon steel additionally alloyed with molybdenum and vanadium, with medium corrosion resistance. It is produced by Damasteel AB itself. It has a good combination of cutting edge resistance, corrosion resistance and mechanical properties, and holds a thin cutting edge well. It has a large number of alloying elements, including manganese, molybdenum, vanadium, chromium and sulfur. With its high hardness, the steel is well machinable – ground and polished, it is excellent for blades of complex geometry and is considered one of the best steels for artistic etching. Several damask packages are produced with the use of this steel, the most popular among them are:

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The DS93X package is a martensitic steel with a Damascus steel pattern. It consists of two different hardened knife steel grades. The light component is RWL34 powder steel and the dark component is RMS-27 carbon steel.

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The Damacore DC18N package is also a martensitic steel. It contains three different alloys. The central core consists of N11X, an alloy steel with a high nitrogen content. The outer layers with the damask pattern consist of RWL34 and PMC27. The steel has high hardness after quenching and tempering.

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Both packages have excellent corrosion resistance and high mechanical strength. These steels also have good ductility and are easy to grind and polish.

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Thus, on the example of powdered damask, we see a harmonious combination of ancient technologies of production of beautiful and strong steel, with the most advanced technologies of powder processing.

A fillet knife is a specialized knife for preparing fillets of fish, meat or poultry. It is characterized by a long, narrow and flexible blade. Good sirloin knives can bend almost in a circle. That is, the main distinguishing feature is exactly flexibility. This knife should work superfine, cutting off the thinnest pieces of fish or meat, often less than a millimeter thick. The knife must also pass over the bones, the spine and tendons, to separate the skin from the meat, leaving a minimum layer of meat and subcutaneous tissue. In addition to removing the skin and separating the meat from the bones, a sirloin knife can be used to cut the product into thin slices (slices). That is why filleting knives are in demand among professional masters of European cuisine, and among cooks specializing in making sushi and other Japanese dishes. Often a sirloin fish knife has a serrated edge for tail and fins processing.

The length of the traditional “fillet” varies from 10 to 30 cm. Usually in serial industrial production, the sizes of such knives are 10, 15, 19 and 23 centimeters. The thickness of the blade varies from 0.5 to 1.5 mm. The width of the blade is from 1 to 3 centimeters. In terms of blade profile, a sirloin knife often has a straight edge, sometimes slightly bent upwards. Narrower in width, the knife is used most often to cut off the fillet, a wider blade separates the loin from the bones. It should be noted that a well-sharpened “fillet” should easily cope with cutting across the side (abdominal) bones of medium-sized fish. And at primary blunting it is quite capable of working due to its geometry without much effort.

The optimum angle that is considered the accepted standard for the cutting edge of a “fillet knife” is 23+/-2 degrees. Professional sirloin knife is sharpened usually under the hand of a particular professional. There is also the elasticity of the blade, and whether he is left-handed or right-handed, based on this some of the approaches can be wider or narrower, etc. Usually, factory knives made in-line are sharpened on a grinder rather coarsely and without a micro grip. And knives that are made or sharpened individually are recommended to be sharpened according to the method of sharpening safety razor blades, i.e. with three facets of micro-piping. For example, such a variant is possible: after skinning preliminary sharpening on abrasive grit from 800 to 1000 at an angle of 18 degrees, final sharpening on abrasive 3000 grit at an angle of 20 degrees, finishing with natural stone or blank with paste at 23 degrees. The direction and the combination of the ribs during finishing are also individual. The criterion of a good sharpening of a filleting knife can be a simple test, when only the skin is easily removed from a tomato and the pulp is not affected.

When talking about the difficulty of sharpening a fillet knife, the main factor to consider is its flexibility. It is extremely difficult to maintain the angle when the blade is thin and flexible. It is especially difficult to do it with a long blade. And if at manual sharpening this issue is solved by precise, extremely easy movements of the approach on the stone, then on sharpening machines with a rotary mechanism light movements alone will not be enough. It is necessary to securely fix the knife, preventing the blade from bending on the tip or handle side and preventing sagging in the central part. To solve this difficult task, the Profile K03 sharpener is equipped with so-called “fillet clamps”. These clamps reliably hold any blade shape, ensuring that the jaws are in contact with the planes of the knife edge and that the blade has open access to the blade for machining. The fillet clamps are based on three basic elements: the base, flat springs, and clamping jaws. Powerful jaws are connected to the base through flat flexible springs, which provide a universal fit and when the knife is inserted into the clamp, the springs change from a free state to a tense state, thus the rigidity of the clamp is significantly increased. Also, the fixing and adjusting screws in the clamp bundle, form a rigid geometric system and at the same time, allow a wide range of adjusting the clamp to any shape of the blade and ensure symmetry of installation.

For sharpening of fillet knives Technostudio “Profile” offers two variants of clamps:

1. Fillet full-milled clamps. They are designed for fixing knives with the thickness of the shank up to 3.5 mm. The shape of the outer surface is radially convex, which allows you to set the minimum sharpening angles of 7.2 degrees. The clamps are made of a single piece of aluminum, allowing to adjust the clamp to any shape of the blade and ensure symmetry of installation. The width of the clamps is selected in such a way as to allow up to 4 clamps to be mounted simultaneously on the frame and securely fix even the most flexible fillet knife. It is possible to move the clamps independently along the entire length of the frame. There is no need for calibration. It is possible to sharpen: kitchen knives, filleting knives, keychain knives, dangerous razors, knives with “scandi-slopes” and other narrow long knives. The recommended knife length for these clips is from 30 to 300 mm. The minimum recommended blade width is 10 mm. The width of the clamp jaws is 21mm each.

2. Single Sirloin Clamp -a special clamp for narrow sirloin knives, with a reduced sharpening angle. The thin jaws of the clamp are made of structural spring-spring steel, which provides sufficient clamping force. The clamp with a modified jaw configuration and with the use of special screws has a maximum minimum sharpening angle of 6.5 degrees per side. The minimum width of the knife that can be fixed by the clamp is 10 mm, the maximum thickness of the blade is 2.5 mm. The clamp fasteners are anodized by default. It is recommended to use this clamp for sharpening small fillet knives as well as small knives with descending bevels like Victorinox and other folding knives and multitools. The recommended knife length for this clamp is from 50 to 200 mm. The width of the jaws of the single fillet clamp is 32 mm.