doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Neutralize cold blue - french grey

Giving cold blue and carding a try to work up a french grey on a simple French boxlock. There are a variety of methods for french grey, and this one with cold blue is prone to developing a bronze tint, which seems to be after rusting of the cold blue. The parts have been oiled to prevent this, but that did not help. Cold blue smells bad too.

Suggestions for other processes?

Vinegar.

Most cold blues like 44-40 Numrichs brand are an acid (selenic?),,I'd go the other way and use an alkali like bicarb/soda or wash it with soap and water.
If I do use that stuff at all and that is rarely, I simply wash & scrub the part(s) with an old toothbrush and common dishwashing soap,,then rinse. Seems to take care of the acid residue. But they will need oiling of course to protect them.
Vinegar is a decent blue/rust remover as well so it may put you back to step 1.

If you're using cold blues like 44-40 from Numrich and the other common types,,they do have a very distinct smell,,and not a good one by most peoples standards! 44-40 does after rust.

Brownells OxphoBlue cold blue does not after rust and none of the 'smell'. I prefer to use it if I use a cold blue for anything.

I second Kutters endorsement of OxphoBlue. For French Grey, try very fine valve grinding compound on 0000 steel wool. Do it in small circles and be careful to even out the color. Try it on a discarded piece first.
Mike

Boric acid in a solution of warm water. Works great and can be bought at low cost on eBay.

Most any of the Ant & Roach killers in powder forms sold in places like WalMart and DIY stores are Boric acid.
Big plastic squeeze bottles with a narrow nozzle on them for getting at them kritters! Cheap too.
I use the stuff as a heat scale shield when making some small tools and such.
Mix a paste of it up w/alcohol. Coat the tool with it. Light the gob up and the alcohol burns off leaving a very brittle but airtight shell around the tool/part.
Bring it up to temp. When quenched, the shell disintegrates leaving the nice, bright and clean piece ready for tempering.
Sorry for the thread drift.

Muriadic or Nitric acid in very dilute soln (1 or 2 tbs /per Qt water) work well to bring out a grey finish. Parts usually need to be aggitated with a small brush with the soln while they are submersed in it.
Room temp!, don't try and hurry it along w/ any heat.

Even up any dark areas w/ 0000 steel wool or better I find those PinkPearl erasers work great. They come in different grits too.
Belgian Brownings color very quickly using Nitric and this method.

If you are Express Blueing (Quick Rust),,placing the parts in the boiling water tank and occasionally plucking them out and carding them will give you a pretty easy and nice grey finish.
Don't coat the parts with any of the bluing soln,,they just get effected by the residual soln and chemicals from the Bluing you are doing that is in the water.
They come out nice and even in my experience. Maybe because the chemicals are in such low % in the water.
Just another of the many ways to get a grey finish.

I�ll try roach powder. Bought some recently to try with some laminate steel. Thanks.