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Forums10
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Jul 28th, 2025
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Joined: Dec 2002
Posts: 43
Sidelock
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OP
Sidelock
Joined: Dec 2002
Posts: 43 |
Has anyone finished a reciever in the dull grey that is referred
to as french grey. Did you use a chemical application or only
the final mechanical finish.
thanks Dave
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Joined: Aug 2003
Posts: 2,941 Likes: 19
Sidelock
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Sidelock
Joined: Aug 2003
Posts: 2,941 Likes: 19 |
Ken Hurst has a lot of knowledge about this process.
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Joined: Feb 2004
Posts: 13,883 Likes: 19
Sidelock
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Sidelock
Joined: Feb 2004
Posts: 13,883 Likes: 19 |
I believe Ken uses a commercial bathroom cleaner with phosphuric acid. Evidently, the acid strength is about right for the etching.
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Joined: Jan 2002
Posts: 10,747 Likes: 1372
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 10,747 Likes: 1372 |
True French gray is an actual hardening process, similar to bone pack case color hardening, with the final quench being in a solution of potassium prussate, instead of water. The "tyde bowl" method cuts back blueing to a tasteful gray color, but, provides no hardening.
Best,
Ted
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Joined: Dec 2002
Posts: 43
Sidelock
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OP
Sidelock
Joined: Dec 2002
Posts: 43 |
Will any common acid do or is phospuric acid the best choice. I have tried using muriatic acid and the result was rather poor. The color is all I want not the protection of case hardening.
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Joined: May 2003
Posts: 221
Junior Member
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Junior Member
Joined: May 2003
Posts: 221 |
True French gray is an actual hardening process, similar to bone pack case color hardening, with the final quench being in a solution of potassium prussate, instead of water. The "tyde bowl" method cuts back blueing to a tasteful gray color, but, provides no hardening.
Best,
Ted Cyanide case coloring is used for French grey at least that's what this shop uses. You might want to look at this link, under Cyanide case coloring. Ron's Gun Shop
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Joined: Jan 2002
Posts: 10,747 Likes: 1372
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 10,747 Likes: 1372 |
I actually looked in France, where actual, little French guys were doing it, just like I said. I don't doubt this guys method, or results, but, it wasn't what I've seen.
Best,
Ted
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Joined: Aug 2005
Posts: 377
Member
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Member
Joined: Aug 2005
Posts: 377 |
Ken Hurst and I are Carolina neighbors and I do some of his assembly,etc. in my shop. We have discussed his method of arriving at french grey several times. If memory serves me it goes like this. 1.Anneal and engrave piece. 2.Color case harden by charcoal pack method. 3.Remove colors using toilet bowl cleaner. 4.Cover surface with the dirtiest diesel crankcase oil you can find. Then Viola', "french grey". Best, Dr. BILL
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Joined: Feb 2004
Posts: 13,883 Likes: 19
Sidelock
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Sidelock
Joined: Feb 2004
Posts: 13,883 Likes: 19 |
Like many metallurgical processes, it sounds like there have been many variations on French Gray, as was posted in a similar thread years ago here. For instance, I doubt that the Pigeon Supers are case hardened then quench etched. More likely, they are hardened as normal for martensitic steel and then etched.
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Joined: Aug 2005
Posts: 1,698
Sidelock
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Sidelock
Joined: Aug 2005
Posts: 1,698 |
Mr/ Chuck, that filth diesel oil I use has a certain amount of sulferic acid in it. The older/longer the oil is kept in the motor, the more acid seems to develop. The etching process of the acid is so minor that the surface of the gun simply turns gray but doesn't apear to have an etched /rough finish. FWIW, Ken
Ken Hurst
910-221-5288
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