Material Highlight: Carbon Black
We are here in celebration of stainless steel’s tough and protective older brother — the nitrocarburized finish that we affectionately call Carbon Black. What initially catches the eye as a matte black coating is the product of a fascinating scientific treatment called ferritic nitrocarburizing, also known as Melonite.
Dating back to the early 20th century, the nitrocarburizing process changes the molecular structure of the shell of a steel or iron object to be far more durable, while the interior remains unchanged. This finish is most commonly used in automobile and industrial parts and firearms, where the end result yields lower friction, increased hardness, and resistance to corrosion even in the harshest of conditions.
The journey of our Carbon Black products starts with a solid steel form, first preheated and washed at extremely high temperatures, then plunged into molten salt nitriding baths at temperatures above 1000°F. Once submerged, the nitrogen and carbon in the bath permeate and fuse with the steel, permanently altering the outermost layer of the product. What we end up with is a smooth, matte black finish that is resistant to whatever wear we endeavor to throw at it.
The soaring temperatures reached during this process would melt other metals like brass, copper, or silver — but steel withstands the heat and is made much stronger for it. In the case of our Carbon Black Wilson & Closed Helix Keyrings, the finish is harder than the brass keys it carries, sometimes resulting in a deposit of brass material that wipes off with ease.
Utilizing the nitrocarburized finish allows for the unique opportunity to reintroduce ourselves to a product that has traditionally been released only in its stainless steel form, like with the recent release of the storied Venn Puzzle in Carbon Black. The holy trinity of Craighill’s traditional Brass, Steel, and Carbon Black offerings would not be complete without this creative design application of what has historically been thought of as a purely industrial process.