So here is something I have not performed yet, dealing with color case hardening finishes and their' preservation.
I picked up a Savage Model 220A 12 Ga Shotgun at auction, actually forgot that I had put a lowball bid on it, and then got notice that I won. Anyhow, she's in need of a bit of care. As you can see from the picture it has some surface oxidation, mostly on the receiver.
So my question has to do with boiling. Most time I boil and card the oxidation when I do my preservations, but I have never done it with a firearm that has a color case hardening finish. While I figure the areas that are oxidized will lose the color, will the boil and subsequent carding remove the color case hardening finish on the sections NOT oxidized?
Thanks in advance!
Bill
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I think you'll lose case colors wherever you card.
Jim is correct. The oxidation that creates those swirls is very delicate. Boiling would most likely greatly diminish if not remove what is left of it, carding would erase any trace it was ever there. Most new factory color-cased finishes will add a clear coat over top to protect them (e.g. uberti reproductions). If you want them to last, keep solvents away, and keep the surface protected. Oxygen will slowly degrade it and make the colors less vibrant over time.
as for restoring, the only way is to redo to he color case hardening process. There is a video on YouTube somewhere of the guys at Turnbull restoration restoring the color case hardening on some old lever guns. They pack the actions in bone black or charcoal mix, heat in an electric furncace to a specific temp for specific time, then pull out and quickly water quench. Also, it's worth noting that the colors only develop in an oxygen depleted environment. So what I described above is really the only way to do it.
I've read of someone having limited success on small parts with an improvised setup of a tin can, and a charcoal BBQ, but the colors are never as vibrant as doing it a more controlled procedure. There is another video I saw somewhere of a guy doing this improvised method to fabricate some leaf springs he needed for an old rifle. worked great for functionally to temper the parts.
There are still gunsmiths around restoring early cartridge firearms such as the first generation Colt single action (much in demand) that do their own case hardening. i saw the work of a gunsmith who worked in a large gunshop, he even case colored a Mauser M98 action. the Mauser looked good too, but his main work was Colt 1873 revolvers.
Some years ago I converted a South American issue Remington rolling block to 22 rim fire, did alot of custom work and found an advertisement in the old Shotgun News for color case hardening from a man in South Dakota, It cost me just under $100.00 including shipping, while not the color pattern Remington used, it looks good to me.
Shop around, you might find a gunsmith to color your shotgun
Jim is correct. The oxidation that creates those swirls is very delicate. Boiling would most likely greatly diminish if not remove what is left of it, carding would erase any trace it was ever there. Most new factory color-cased finishes will add a clear coat over top to protect them (e.g. uberti reproductions). If you want them to last, keep solvents away, and keep the surface protected. Oxygen will slowly degrade it and make the colors less vibrant over time.
as for restoring, the only way is to redo to he color case hardening process. There is a video on YouTube somewhere of the guys at Turnbull restoration restoring the color case hardening on some old lever guns. They pack the actions in bone black or charcoal mix, heat in an electric furncace to a specific temp for specific time, then pull out and quickly water quench. Also, it's worth noting that the colors only develop in an oxygen depleted environment. So what I described above is really the only way to do it.
I've read of someone having limited success on small parts with an improvised setup of a tin can, and a charcoal BBQ, but the colors are never as vibrant as doing it a more controlled procedure. There is another video I saw somewhere of a guy doing this improvised method to fabricate some leaf springs he needed for an old rifle. worked great for functionally to temper the parts.
I am not a expert by any means on colour case hardening, but I recall reading most (basically all) colour case hardening finishes on modern reproductions aren't actual case hardening resulting in that colour, rather a chemical solution they apply to the metal resulting in that pattern instead. That could also have a fair bit as to why they use clear coats as the chemical reaction is only on the very surface and likely isn't as deep as a classic case hardening procedure.
case hardening finishes on modern reproductions aren't actual case hardening resulting in that colour, rather a chemical solution they apply to the metal resulting in that pattern instead.
Somewhere I have some information that indicates cyanide as a possible element that was used to produce some of the vivid colors.
When packed in bone/ carbonaceous materials then quenched in a bath of water that a had a small bubbling vent that supplied air to keep the mixture rolling or bubbling.
As far as I recall , there was also maybe a few drops of oil or something in particular that was allowed to float on top that acted as an agent and helped to produce the colors.
Otherwise ,when done incorrectly a mottled gray appearance was usually the result without a bit of experimentation involved to learn the process completely.
And then finally, that it was a method that was usually guarded among the persons doing the work.
Not to mention the use of cyanide and the hazards associated with it.
The question of cyanide in case hardening products cropped up some years ago, elsewhere. It was "suggested" to me that the cyanide used in case hardening products nowadays is in a "safer form" than it use to be in the past, however, this has not been confirmed. Does anyone know if this is correct or not?
It use to be considered a, potentially, highly dangerous product because of the cyanide content.
I have a book on gunsmithing written in the 1930s ('Advanced Gunsmithing' by W.F. Vickery). The stuff they describe doing in it would blow your mind, a lot of it isn't legal to do today. Packing barrels in asbestos, using cyanide (the advice being given is to have a small electric fan blowing the fumes away from you as they are toxic), etc.
Historically case hardening was often done with crushed animal bones, a special blend depending on who did it. I believe it was Marlin who was known for having the nicest looking case hardening in the day and it was a closely guarded secret by the man who did it. Modern case hardening is done with products like Kasenit which hardens it but doesn't produce the fine colours the historical methods did. Most people don't case harden anymore though as it was mainly done historically due to the lack of control on steel (much of the steel of the time was based on regions and such, ex. Swedish steel was known for its corrosion resistance due to the natural amounts of nickel in the ore used to make it, it was also mostly mild steel by todays standards), vs. today when we have all the control we possibly could need.
The exact contents/mix/ratio of what metal was packed in before it went into the furnace would have been proprietary. Different mixes produce different types of colors.
Basic example...notice the colors aren't as vibrant as other examples.
This one is mighty pretty...but I don't think they say what's in their mix