doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Case Colouring - Cyanide vs Charcoal/Bone

Sunlight has nothing to do with case color fading. Abrading them does remove them. Repro Parkers are hard to color because the lump the floor plate attaches to is braised on and not forged. The copper, tin, zinc contaminates the heat treating furnace and spoils results. This info was provided to me by Oscar. He had to redo his home made furnace to get rid of the bronze alloy that contaminated his fire brick.
bill

Parker Repros are not Cyanide colored. In fact they are not color hardened at all. They are made of modern steel, not requiring case hardening. The colors on them is actually a sort of stain applied to the metal to replicate the look of case coloring. The color will come right off easily with chemical stripper.

I have had a few Repros bone charcoal colored (by Turnbull) and the results were excellent. Just like any original parker.

The tang screw bridge on Repro trigger plates is a separate piece that is soft solderded in, not brazed. All you have to do is tack weld the four corners of it down before coloring and it will stay put through the process.

My query was to try and ascertain which of the two methods might be more durable. I am not interested in which might be more attractive although I do have my preferences.

Whether sunlight has nothing to do with fading is an interesting question as others on this forum and the Parker forum might disagree. I'll defer to their experience.

Whether salt, perspiration or other, fade the colouring, I have not experienced it on my 311.

I have had both processes done on custom guns that I have made and the cyanide colors have always been Much more durable than pack hardened colors. Some of the cyanide colors have been equally attractive,just as hard and corrosion resistant as well. The decision which process to use was based on the steel parts to be hardened.

Does anyone know if Heinzelman & Sons is still in business or offering to cyanide color firearms? With all the hazards of cyanide and the advent of more modern heat treating processes I can't imagine many shops still mess with real cyanide salt color case hardening.

Not double guns but at about the 2:20 mark the Uberti SAA clone salt bath hardening process is shown - https://m.youtube.com/watch?v=qYOJa8ZNxmE

They are not in business any longer. I tried for two years to reach them to no avail, and I finally called the local post office who told me the address for Heinzelman & Sons is no longer a good address.

Ron's Gunshop still does cyanide case hardening.

http://www.ronsgunshop.com

SRH

Beauty is of course as they say "In The Eye of the Beholder". Do note that I added "Personally" I have never seen a cyanide job that to me was as attractive as the bone charcoal colors.
As to hardness, note also I did not say the bone colored jobs were harder than the Cyanide, what I said was they normally have a deeper depth of case. The term "Case Hardening" comes from the fact one puts a hard shell/case around a soft core. According to Machinery's Handbook most cyanide hardened parts receive a depth of case of as I recall of .001"-.003" while pack hardened parts can be much deeper than this. In either case the depth of the Color is microscopic being only on the surface. The color being worn away is no indication at all that the hardness of the case is gone, its still right there doing its job.

WAY beyond my knowledge, but as SDH explained, the steel may determine the color case hardening method.
We know prior to WWII U.S. maker's actions were AISI 1020, which with 1018 is easily pack hardened.

Hopefully Bro. Tom will elaborate as I couldn't find my reference, but Hunter Arms was using cyanide for some parts. I believe Charles Jerred was briefly blinded by an accident in the Heat Treating Dept.

8620 seems to be the modern choice
http://www.suppliersonline.com/propertypages/8620.asp

4140 can be color cased but apparently with more difficulty, and requires an oil rather than water quench with careful attention to the temperature used.

What appears to be a 2-fer; cyanide + torch?

A friend has a Beretta SxS and the colors on the sidelocks look just awful - like someone used a torch. There's just two blue streaks going vertical, kind of like Drews' picture, but not as many.

Some modern guns made of alloy steels have been chemically colored, "From the Factory". Note that this is just colored, Not Color Case Hardened. Part is heated to around 200�F & the chemicals painted/daubed on. This can be done with Cold Blue.
Note also this is not the same process as "Torch Coloring" where the torch is held on one spot long enough to produce the color desired & Also Destroy the previous hardening. The Chemical coloring does not affect the integrity of the metal but of course will never look as well as a bone charcoal job, though can look as well as a lot of cyanide ones. I have no idea how well it holds up, but at least is easy to do again.