One method of coating is to sand the blade in one direction with increasing grades of abrasive grit. This creates a layer that is free of reflective glare. This type of coating is suitable when you want to show the edge of the blade. But, it provides average corrosion resistance.
High-end knife makers value this approach. The result is a minimalistic and sleek design valued by collectors. The effort to create a satin finish knife is sometimes more. This increases in price and is the reason why they are seen as part of luxurious collector knives.
> Stonewashed Finish
The stonewashed finish is variable. The blade is put into an abrasive material. The way it is put, the abrasive that is used, and the way the blade is finished will determine the looks of the blade afterward.
At times, the knives are first acid-washed before they are stonewashed. This helps to improve the knife's corrosion resistance.
> Titanium Nitride Coating
This type of coating is used on steel, carbide, titanium alloys, and aluminum parts. This type of coating is also called TiN coating. This coating helps with protecting cutting, hardening, and sliding surfaces and providing non-toxic coats to surgical devices.
This type of coating is also applied to industrial knives. This helps in reducing blade surface friction and strengthens the cutting edge against premature wear.
> Gun Blue
This method of coating is probably one of the oldest. It is still used today, this method is in use. Its name is derived from the blue-black gun barrels that we get after going through the process. The process leaves dense thin layers of magnetite on the surfaces.
It is to be noted that the actual method involves hazardous chemicals. But, there are other safer treatments with a similar look. The method earned its name because of its easy use, cost-effectiveness, and safety.
Moreover, you can get these products at your local gun shop. But, keep in mind that this method is for touch-ups not for the entire coating of the blade. Also, you can only gun-blue your blade if it's stainless steel. Since they are not entirely rust-proof, you must avoid wet applications and oil their surfaces regularly.
But, as they are cheap they save you a lot of time in maintenance.