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After the blade of a knife is completely forged and heat treated, it needs to get some final touches to give the surface its final looks and character. This process, known as blade finishing, is important not only for the looks of a knife but for the service properties as well. Explore various options of blade finishing in this brief guide.
A blade is finished to achieve a certain grit on the finished surface. A low-shine finish has 280 to 320 grit, while a mirror-shine polish has a very high grit number providing a perfect sheen. The average standard for high-quality knives is about an 800-grit finish. A higher polish shine can be achieved with buffing using chrome oxide (white chrome, green chrome) or by hand polishing with a very fine abrasive paper. Japanese water-stone allows achieving a grit as high as 10,000 to 12,000.
A hand-satin finish is worked by sanding the blade through gradually increasing grades of abrasive grit. A good satin finish showcases the shapes of the blade and reduces reflective glare. This type of finish is usually applied to upscale custom knives that require a hand-made sleek look valued by collectors. With an increase in grit number, finer abrasives will produce smoother lines and a cleaner finish. Satin finishes are also used on the handle or fittings of a knife to improve overall appearance. A thorough hand-satin finish performed by a seasoned master can increase the price of a knife.
A mirror polish provides a bright, glary sheen to the knife blade. This type of finish requires sandpaper somewhere from 2,000 to 4,000 grit.
The resulting shiny finish has several advantages: first of all, it is aesthetic. Then, a mirror-polished knife is much better at push-cutting operations, such as shaving, chopping, or carving. Merely sharpening a blade does not provide good edge retention: a well-polished blade is needed, and a high-grit polish will reduce the risk of dulling. Remember, that mirror polish is easily scuffed, so this type of finish is more likely to be used on high-end, showpiece knives. Applying a mirror finish takes a lot of skill, and retaining this upscale polish requires careful maintenance.
Stonewashing distresses the blade using friction to create a whacked look. During the process, a knife blade is run through the dryer with small stones or other abrasive material to create grazes on the blade surfaces. The technique speeds up the normal aging process, removes sheen, and hides scratches and defects. The knife may look differently after the stone washing procedure, depending on the type of abrasive used, the tumbling technique, and the method of prior finishing. Stonewashing is an affordable option that may produce a curious finish with primitive household equipment. Remember, however, that stone washing dulls the knife blade, so you’ll need to resharpen it afterward.
Bead blasting is an affordable, less aggressive surface finish option. It is a flexible surface finish process that involves shooting glass, ceramic, or steel beads at high pressure to give a uniform finish to the material. The versatile process works with various materials from stainless steel to brass and even plastic, and is suitable for a wide range of purposes. Different results, concerning visual effect and roughness, may be achieved depending on the size and shape of the blasting beads, the speed, and the pressure during
the procedure. Typically, a semi-polished, satin finish with a soft, matte look is achieved. A higher of lower grade of reflectivity and a darker or a lighter color can be achieved, depending on the media. The surface can be made more or less dull, satin, or rugged. Bead blasting is known to result in a smooth and even finish. It also improves the mechanical strength and aesthetics of the surface. With proper settings, the bead blast finish can even harden a material and increase its durability.
Knives meant for heavy-duty use may require a coated finish. These typically come in darker colors, provide great rust resistance, and reduce wear and tear. You should be cautious with coated finishes as they can be scratched off easily. In such a case, they should be recoated to restore their appealing appearance.
A quality coating on the blade can considerably increase the working lifespan of the knife. Some coatings (for example, DLC – Diamond-Like Carbon) are expensive, but they will be worth the splurge if you consider the added value of corrosion prevention and easier maintenance of your knife.
Gun blue is as popular today, as it was long ago. This old method of steel coating derives its name from the blue-black color imparted to gun barrels after a treatment. Dense layers of black iron oxide (magnetite) left after the process protect the surfaces and the bluish-black color of the “gun blue”. Perhaps the oldest and most popular technique, bluing is still widely used as it is very easy, relatively safe, and cost-effective. The cheapness of the bluing method saves a lot of maintenance efforts and expenses. However, bear in mind that bluing products are intended for minor touch-ups only, and the procedure shouldn’t be applied to a whole blade. A blade is not perfectly corrosion-resistant after bluing, and you should be prepared to blue your blade on an ongoing basis.
Anodizing (or anodization) is an electrolytic process that converts the surface of a metal (for example – titanium) into a durable protective coating of metal oxide. The process is accomplished by immersing the metal into an electrolyte bath. An electric current passing through the medium releases oxygen ions to combine with metal atoms and form metal oxide at the surface. The oxide structure originates from the metal substrate and is fully integrated with the underlying metal, so it cannot chip off or scale.
Anodic coatings are highly resistant and timeproof, they remain stable and unfading even in areas subject to rough operation and abrasive abuse. Anodized surfaces are known to resist corrosion better than non-treated metal. The lifetime of the anodic finish depends on the thickness of the anodic coating applied.
Teflon is a type of plastic sprayed on various surfaces and then baked to create a non-stick, waterproof, and nonreactive chemical coating. It is used to prevent buildup from various adhesive materials during use. However, remember that Teflon coating is not good for kitchen knives. The only FDA-approved coating cures at a high temperature that can affect the heat treatment of an industrial knife. Therefore, knives to be used in the kitchen should not be coated with Teflon.
Titanium nitride (TiN) coating is a hard ceramic powder that is wear-resistant and chemically inert. It is used on various tools and surfaces, increasing tool lifespan two to ten times. TiN coatings have a broad range of applications due to great practical properties such as high hardness, corrosion resistance, reduced friction, and wear resistance. TiN coatings are used on various metals, for hardening cutting, and sliding surfaces. TiN is often used for providing inert coatings for surgical devices. When applied to knives, this coating reduces friction on the blade surface and hardens the cutting edge against wear.
The titanium carbo-nitride coating (TiCN) is a coating type that offers a high hardness combined with good toughness, resulting in additional tool life. Carbon in a TiCN coating increases hardness by nearly 80 percent over a TiN film. TiCN has the highest lubricity of all the TiN coatings, providing great hardness and wear resistance. It is known to achieve superior abrasive wear resistance. Being an excellent all-purpose coating – TiCN is commonly used for cutting or forming harder materials, due to its higher surface hardness.
Hard chrome, also known as industrial hard chrome, functional chrome, and engineering chrome, is an electroplated surface finish technique. During the hard chrome electroplating process, chromium is deposited onto a surface from a chromic acid solution. Combined with a base metal substrate, a hard chrome finish achieves the high quality and efficiency of the product. It is known for its wear and corrosion resistance and, especially, low friction characteristics. Hard chrome plating is widely used due to its effectiveness. Industrial hard chrome finish increases the working lifespan of a knife as it protects the blade from oxidation and improves surface hardness.
BlackWash is a specific knife blade finish, a combination of black coating and stonewash finish. Black coating uses a chemical bath to transform the upper layer of the steel to magnetite. It improves corrosion resistance and adds an aesthetic look. After coating the blade black, the stonewash finish is added. The whole process produces a vintage, worn look like that of a used tool. Also, the resulting surface structure hides use scratches and adds knife protection. This variation of the stonewash finish has become quite popular over recent years.
DLC (Diamond-like Carbon Coating) covers the blade with a thin film of carbon atoms with a hardness similar to that of a natural diamond. DLC is the hardest coating used on knife blades. Along with the superior hardness of the blade, it features very high abrasion resistance, low friction, and excellent corrosion resistance. The pitch-black color of the DLC coating also provides anti-reflection properties for knives. Surfaces coated with DLC withstand wear from chemical agents, dampness, and other atmospheric conditions. They are immensely durable and have a longer operation life.
In this process, a fine powder is applied with an electrostatic spray gun that causes powder particles to adhere to the steel and then cured under heat. The dried powder is known to produce a smooth, even, durable, and very tough coating. The process is now applied to a variety of products, including knives.
PVD (Physical Vapor Deposition) coating is also known as Thin-Film Coating. During the process, a thin film of a solid material – metal and/or ceramic – is vaporized in a vacuum environment and deposited, by condensation, onto the blade surface. The coating, deposited atom by atom, forms an extremely pure multi-layer, bonded structure that greatly enhances the look and function of the blade. PVD deposited films at the atomic level, thus allowing to finely control the structure and density of the coatings. PVD is widely used at the industrial scale and is capable of producing coatings with excellent service properties. PVD coatings are known to provide high durability, hardness, lubricity, great corrosion resistance, and scratch resistance. PVD coatings greatly reduce friction and block damage from atmospheric factors.
Cerakote is a polymer-ceramic composite coating made out of resin and hardener. The unique formula provides an excellently hard finish and makes Cerakote a high-performing coating that improves several functional properties such as abrasion resistance, corrosion immunity, and impact strength. Cerakote is baked onto the working surface, that is, cerakoted blades are subjected to high heat when applying the coating. The process is known to provide superior protection against such factors as chemical attack, heat, and ultraviolet, making it a perfect coating for outdoor applications.
Knives are practical workpieces, each one having a specific function. The coating you apply, apart from being a significant aesthetic component, can make a positive difference in the performance and the working lifespan of your knife. Careful consideration of what environments and how your knife will be used will help you choose the right blade finishing for your knife.
This video examines various coatings applied to knife blades, focusing on durability, corrosion resistance, and performance enhancement. Tests include chemical stability and impact on blade sharpness. Featured coatings encompass Chromium Nitride, DLC (Diamond-Like Carbon), WCC, and Cerakote. Results provide comparative insights valuable for manufacturers, enthusiasts, and professionals in knife-making.
YouTube video by: Gough Custom.
The FAQ section provides concise, informative answers to common questions about knife blade finishes. It covers topics such as the impact of different finishes on blade maintenance, the possibility of finishes wearing off over time, methods to change or reapply finishes, the relationship between a finish and blade sharpness, and specific care instructions for unique finishes like acid wash or blued. This section serves as a quick reference guide for readers seeking practical advice and insights on maintaining and understanding the various aspects of knife blade finishes.
Different blade finishes serve various purposes, primarily affecting a knife’s appearance, performance, and maintenance needs. Satin and mirror finishes enhance aesthetics and corrosion resistance, ideal for culinary and decorative knives. Bead blasted and stonewashed finishes offer a rugged, non-reflective appearance, suitable for tactical and everyday carry knives and are effective at concealing scratches. Black oxide and DLC coatings provide additional durability and corrosion resistance, commonly used in military and high-end tactical knives. Each finish has specific maintenance requirements and is chosen based on the knife’s intended use and desired characteristics.
Yes, the finish of a knife blade does affect its maintenance. Finishes like satin and mirror require regular polishing and cleaning to maintain their appearance and prevent corrosion. Bead blasted and stonewashed finishes are more forgiving of scratches and require less frequent maintenance but may need protective coatings to prevent rust. Black oxide and DLC coatings are highly durable and corrosion-resistant, needing minimal maintenance. The choice of finish should consider the user’s maintenance preferences and the knife’s intended use.
Yes, a knife’s finish can wear off over time, especially with frequent use and improper maintenance. Finishes like bead blasted, stonewashed, or coated surfaces (like DLC or black oxide) are more durable but can still degrade, showing wear or losing their protective qualities. Regular maintenance and proper usage can prolong the life of the finish.
Yes, you can change or reapply a finish to an existing knife, although the feasibility and results depend on the knife’s material and the desired finish. Processes like polishing, bead blasting, or applying coatings often require specific tools and expertise. For best results, consult a professional knife smith or a specialized service. DIY methods are available for simpler finishes, but caution and proper knowledge are essential.
No, a blade’s finish does not directly affect its sharpness. Sharpness is determined by the blade’s edge geometry and the honing process. However, certain finishes can influence the blade’s overall performance and maintenance, which indirectly impacts how well the edge holds its sharpness over time. Regular maintenance is key to retaining a blade’s sharp edge.
For special finishes like acid wash or blued, follow specific care guidelines to maintain their appearance and integrity. Acid-washed blades require regular cleaning and oiling to prevent rust, especially in humid conditions. Avoid abrasive materials that can damage the finish. Blued finishes, used for both aesthetics and corrosion resistance, also need regular oiling and gentle cleaning with a soft cloth. Avoid harsh chemicals or scrubbing, as these can strip the finish. Store in a dry environment to prevent corrosion.
The world of knife blade finishes is a testament to the perfect blend of aesthetics, function, and craftsmanship. As we’ve delved into the myriad finishes available, it’s clear that each brings not just a distinct look but also offers unique benefits, from rust resistance to reduced glare. A blade’s finish can be the silent storyteller of its journey—from the forge’s fire, through the hands of its maker, to the tasks it performs in the hands of its owner. Whether you’re a knife enthusiast, a seasoned collector, or someone appreciating the art of bladesmithing, understanding these finishes enriches our appreciation of the knife as both a tool and a work of art. Remember, behind every gleam, texture, or pattern, there’s a purpose, a technique, and a craftsman’s touch. Choose wisely, care deeply, and let your knife tell its story through its finish.
Author: Aleks Nemtcev | Connect with me on LinkedIn