How durable is color case hardening?

[gjn]

I love the look of the color case hardened frames on many of the custom handguns shown on this site. I was curious though how durable is it? Does it hold up well on a gun that get a lot of use? Thanks.

[vonfatman]

I've heard that a case hardened finish can be dulled by exposure to a bunch of sunlight. I make no claims as to this being true....it's just what I have heard.
Bob

[JM]

I've heard that some such as Turnbull adds a protective coat of sometype of sealer over the colors. Don't know if that is true & what type of sealer would stand up to gun cleaning solvent. I try to keep a good coating of oil on mine.

~JM~

[magman]

Mine isn't doing so well. I spoke with Mr. Turnbull and he said send it back and they will refinish it.

[jamesjames]

As an artist with some background in blacksmithing, steel sculpture, and iron work, I can tell you that color case hardening is part of the family of color effects applied to metals that are more "fugitive" or superficial in their durability.

The most fugitive, or fragile of metal colorings is color resulting from heating. When steel is heated in a forge, the surface color changes through differential heating of the hot end in the fire and the cooler portions further away from the fire. That's where the blues, violets, greens and "straw" colors appear along the length of the iron bar as it is heated (before it reaches 1350 degrees F when it begins to glow a dull red). The coating is very thin on the metal surface and can be easily brushed off. This is the most superficial of the coloring capability of iron.

By the way, iron is not especially easy to create a patina on, so there are a narrow range of surface colorings that can occur. Oxidation, or rust, can be a range of warm to reddish browns based on the red oxide of iron. Gun Bluing is a chemical patination process to oxidize the iron into magnetite, a form of iron oxide that is black.

As you treat metal with chemicals to create oxidation of the surface, the resulting patina sits on the surface and also penetrates slightly into the top layer of the metal depending on its porosity and other metallurgy aspects.

Color Case Hardening heats the iron in a charcoal and calcium carbonate mixture (bone, leather). The charcoal in the crucible helps to keep a low oxygen atmosphere around the iron so the reds, violets, and straw colors can form more brightly on the metal surface. The colors intensify in the quenching process when the iron is quick quenched in water or oil. This case hardens the metal and helps to freeze and slightly intensify the colors of the case hardening process.

Its important to protect metal finishes with lacquers, waxes, or other clear coatings to preserve the color effects of patination processes.

[Markbo]

But James, even with some 'cover' won't CCH still fade with exposure to UV light? Isn't that the culprit to causing fading?

[jamesjames]

clear coats also provide some protection from UV rays. Inrcalac was developed as an outdoor sculpture durable clear coat for sealing surfaces to protect the patina/colors from fading in sunlight. Mostly used for cast bronze sculpture.

All metal surfaces need to be protected from oxidation, wear and UV rays. Even Johnsons paste wax works as a good metal protectant. Unfortunately, it tends to melt off a hot gun barrel.

I tend to wax my guns to protect from the elements. I have a suspicion that there is some kind of clear coat applied to most new guns to help seal the surface. Even oils, when applied thin, and wiped carefully, can offer protection to metal surfaces.

But if you are a cowboy riding the range every day in the elements, you are going to see wear on blued and CCH surfaces over time.

[Robster]

But if you are a cowboy riding the range every day in the elements, you are going to see wear on blued and CCH surfaces over time.

Yes, but the wear on a gun like that is also an extremely attractive patina. Honest wear, not rust or blue that came off from blood or other liquid has a great look that has you think the gun has a story to tell. I do like honest wear on a gun as much as a fresh bluing and case hardening.