Case color restoration?

[edgarspencer]

Like "fluid steel", "bone-charcoal" has become standard phraseology, when it is used to describe either the material, or the organic heat treat process. Both terms are used so often, they are automatically considered correct. Fact is, all steel was, at it's origin, fluid. 'Fluid' somehow got tossed into many peoples description of barrels other than composite, such as damascus. Maybe Sir Joseph Whitworth's process of forcing molten steel, under pressure, into ingot molds is the source.
Likewise 'Bone' got tossed into the name for a heat treat process which imparts a carbonaceous layer when steel reaches it's upper critical temperature.
Bone is simply one of the ingredients some used to add carbon, but many organic materials, high in carbon, are used.
Two of the most commonly used ingredients, used by Winchester Repeating Arms, and Colt Patent Firearms Mfg Co. were scraps of leather shoe soles, and horse hoof clippings. In fact, Colt didn't use bone,
per se, but coarsely ground bone, or, bone meal.