The finish quality of the blade is determined by the Grit of the finishing grind. These can range from a low-shine 280-320 grit finish to a mirror-shine. The high polish shine can be accomplished by buffing with chrome oxide (ex. white chrome, green chrome), hand rubbing with extremely fine wet-or-dry abrasive paper, or with a Japanese water-stone, which has an approximate grit of 10,000-12,000. Most high quality manufactured knives have about an 800 grit finish.
Why Coat a Knife Blade?
Teflon Black Nonstick Coating
Titanium Nitride Coating
Titanium Carbon Nitride Coating
Electroless Nickel Plating
Probably the oldest steel coating in existence, gun blue is still in use today. The name is derived from the blue-black color gun barrels acquire after going through a treatment that leaves thin, dense layers of magnetite on their surfaces.
While actual gun bluing involves hazardous chemicals, there are several safer treatments that leave a similar look. One of the reasons cold bluing earned its popularity is that it’s relatively safe, extremely easy, and cost-effective. You can buy similar solutions at your local gun shop, but bear in mind that these products are meant for carrying out minor touch-ups: you shouldn’t cold blue your whole blade with them.
No matter what bluing process is used, it can only be done on non-stainless steels, and the blade is not completely rust-proof once done, so don’t use it for wet applications. You should also be prepared to oil blue surfaces regularly. On the positive side, bluing is cheap, and a gun blued surface saves a great deal of maintenance time and money.
Coated finishes, which tend to come in black, gray, and other darker colors, are often associated with knives meant for rugged use. Coatings provide excellent corrosion resistance, as well as reducing wear, tear, and glare.
One caveat to coated finishes is that they can be scratched off just like any utility coating, resulting in an unappealing appearance. Fortunately, they can be recoated to restore their beauty and functionality.
Having a coated knife can significantly extend the life of the blade. Coatings such as DLC (Diamond-Like Carbon) can be costly, but they are well worth the price if you consider that they add more corrosion resistance and reduce the amount of work required to maintain the knives.
TEFLON BLACK NONSTICK COATING
This coating, which is engineered to be more durable than what’s found on consumer goods, is similar to that on frying pans. It is typically used to prevent buildup from food, adhesives, plastics, and similar materials during use.
Bear in mind, however, that the only FDA-approved coating cures at a high temperature that can affect heat treatment of an industrial knife, so blades meant for food preparation should receive another type of coating.
TITANIUM NITRIDE COATING
Also known as TiN coating, this hard ceramic powder is often used as a coating on titanium alloys, steel, carbide, and aluminum parts. Applied as a Physical Vapor Deposition (PVD), TiN is used for hardening and protecting cutting and sliding surfaces as well as providing nontoxic coatings for surgical devices. The coating is applied to industrial knives to reduce friction on the blade surface and to strengthen the cutting edge against premature wear.
TITANIUM CARBON NITRIDE COATING
This coating is used in the same applications as TiN coating but it performs better in certain applications due to its higher surface hardness and is commonly used when cutting or forming harder materials. It supports both longer blade life and higher productivity.
ELECTROLESS NICKEL PLATING
This coating is commonly used on industrial blades due to its smooth surface and ability to prevent the buildup of materials. Electroless plating produces an even metal layer regardless of the surface structure, unlike electroplating, which experiences uneven current density. It has many industrial applications, ranging from decorative to wear-resistance and corrosion-prevention. Powders can be suspended in a bath to create composite coatings.
Hard chrome plating is one of the most effective and widely used finishing processes. Such plating is usually applied to prevent corrosion and abrasion. Additionally, industrial hard chrome increases the durability of a product because it protects the blade from oxidation while retaining surface hardness.
A hand satin finish, which provides average corrosion resistance, is achieved by sanding the blade in a single direction with increasing grades of abrasive grit. The goal is to create a surface that is free of reflective glare and suitable for showcasing blade bevels.
Those who make high-end knives tend to use this approach, as the result is compatible with the minimalistic and sleek designs valued by collectors. Another reason why hand satin finish is often seen on luxurious knives is the effort required to create it, which can drive up the price.
As the name suggests, a mirror polish is a finish that provides a highly reflective surface and smooth sheen to the knife blade. Applying it requires a lot of skill, and maintaining that flawless polish calls for a similar level of maintenance. Mirror polish is easily scuffed, so you’re more likely to use it on knives made strictly as showpieces.
A stonewashed finish is a highly variable one where the blade is tumbled in an abrasive material. Despite being fairly sheenless, it hides scratches and dings well. The type of abrasive used, the way it is tumbled, and how the blade is finished beforehand can all determine how the knife looks afterward. Sometimes, knives are acid washed to improve corrosion resistance before being stonewashed.
Blade heat treating (or heat treatment) is a group of industrial, thermal and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve the desired result such as hardening or softening of a material.
Although to a beginner it might seem that a quality blade is everything required to make a knife a perfect cutting tool, the reality is a bit more complicated. The grind is an aspect often overlooked by knife owners, and every true knife lover has to understand how the grind impacts the use of a knife.
The word ‘grind’ stands for the shape of knife’s blade and depicts how exactly the blade is made thin enough to cut with it. Explore the different edge types, their properties and strengths, to better understand how to have the best of your knife.