Cold Blue Experimenting

[painter777]

Muratic Acid works great, just be careful of the fumes.
I use it full strength on gun parts.
We work with it quite a bit at work and in our shop.
Stripping old lead paints and varnishes off of milled, stainless or cast steel hardware from antique pieces being built in to new builds.
NOT FOR BRASS OR COPPER.....unless your painting over it again.
Before a Acid dip.......
I like to de-grease/ de-oil a part first, then dip into the acid. After it's stripped the old finish....I rinse it in water and blow dry ASAP. Final clean with Alcohol, M.E.K. or Lacquer Thinner then blue or park.
Had a Stainless Steel tank made at the local farm repair for $45.00.
Big enough for a barreled receiver. Smaller parts I use a smaller SS tank.
I like the Radocy Zinc Park. Use a 2 cycle oil with some green tint added for the after park oil bath.

Charlie-painter777

[INLAND44]

Charlie; I also like to play with cold blue but have yet to try Oxpho in any form. A guy showed a great old 1911 with some pitting on a forum the other day that had practically no blue remaining. I wanted to suggest he take it to somebody that knew how to cold blue and get it blackened without any surface prep other than a good cleaning and wire brushing. This way he would be doing no damage and the gun would look better until he made up his mind about a possible restoration. I don't use Muriatic acid - I just haven't tried it. I use one of several brands or liquid rust remover containing Phosphoric acid which is not really dangerous to work with. It will remove any blue, cold or factory, so you have to realize that. I didn't make that recommendation because those guys would have flipped over the idea of cold-bluing a M1911, regardless of the fact that it can be instantly removed for a real restoration. If you see a table at a big gun show where the guy is demonstrating 'Van's Instant Gun Blue', check it out. 'Van's' is great, but those vendors give you a whole tutorial on cold bluing and do perfect touch-ups right in front of your eyes. Simply using the right blue the right way really can have good results. Also, it's not usually necessary to remove any old factory blue first - the right methods will equalize the color. So, I really don't use the acid unless I want to completely strip a part. One of my secrets is to not use any petroleum products or solvents at all during prep. Hot water and dish detergent does the trick along with heavy brushing. If I plan to 'card' with steel wool, I'll also wash it first to remove any factory oils that prevent rust in the packaging. You can blue a large piece like a slide or frame using boiling water in a glass dish with some cold blue added. It blackens almost instantly, particularly when there are a few drops of dish detergent in the water - this stuff is really the secret - it breaks surface tension and gets the chemical to the steel. With this method you have to card off the black sludge that forms pretty much like 'rust blue'. You definitely have to wear Nitrile mechanics' gloves because the black sludge is hard to get off your hands. Finally, cold blue done right actually is blue - it doesn't always have to be black, although that is the easier color to get.

[painter777]

Thanks Inland44,
that's some good info.
Someone else sent me a E-mail about Van's. I'd like to look into it.
I appreciate your help.

Regards
Charlie