Rust Blueing Barrel plugging Truth

Do not use bore plugs for hot caustic bluing

Never
Never

Not a good idea, the heat expand the air will blow out the plug and the bluing salts on you.

I tried and it is a stupid idea. I have the scars on my arm to prove that.


As for rust bluing or parkerizing , never used plugs either -just cleaned out the bore.
 
Rust bluing is the only type I do anymore. It's just too much of a hassle to get shed of the depleted bluing salts when using that method.

I used to plug the bores with black rubber, tapered stoppers. These days I paint three coats of shellac in the bore and let it dry for a couple of days. Then the rust bluing process begins. After I get the "black" that I want, the bore is scrubbed with a bronze wire brush and acetone to get the shellac out. Or, one of those black rubber stoppers is used to plug one end and then the bore is filled with acetone to detach the shellac and then flush it out and into one of the beer cans that was emptied during the waiting period. ;)
 
SGW Gunsmith, what do you use to "paint" the shellac in the barrel? I would imagine a barrel mop? [Seems legit]

What about capping one end, filling the barrel with shellac, draining back into a container, uncapping for a while for the shellac to dry and repeat a couple of more times before blueing?
 
Bore mop...........is exactly what I slather the shellac in the bore with. It goes pretty quickly using the bore mops to "paint" three coats in the bore, mainly to make sure complete coverage has been achieved. After the bluing has been completed, I'll coat the fresh bluing with RIG and let that neutralize the rusting process for at least 24 hours. Then, another wool bore mop is used that's soaked with acetone to remove the shellac. Gotta be sure the area has moving air to get the acetone fumes away from the work area.
 
Rust Bluing is what I am most interested in as well. Since I am having to teach myself this art instead of having the luxury of a school, I am learning about the various methods now. I thought the Bore mop [yes I said barrel instead of bore earlier] would have been the simplest. Thank you so much for the reinforcement.
 
Shellac dissolves in alcohol, so it's easy to remove. I would do that if I were doing steam cabinet rusting before the boil. When I'm just putting a solution like Pilkington's on, I don't have a problem with bore rust. I can see how coating the crown of a muzzle might get a little solution inside, though, so the shellac idea would guard against that. You could also pour some liquid asphaltum (pitch) through the chamber and bore and let it dry. It's sold by art supply places as an etch-resist for printing plates. It dissolves out with odorless mineral spirits.

The boiling itself, assuming good water, is something you dry immediately while the metal is still boiling hot and evaporates water off fast. Not only does that not cause bore rust, at that temperature it actually forms a micro-thin layer of blue oxide on the surface by reacting with oxygen in air. Not only does it not cause rust, it protects the steel. Not a lot of protection, but a little. If you have hard water, the deposits can block that blue layer forming and attract moisture later. I used either distilled water or deionized water. Both work. I don't have one, but a reverse osmosis system should produce good water for it, too. I don't know about rain water. It's acidic in some places. I'd want to check that and titrate it to neutral pH (7) if needed.

Since it takes a minimum RH of around 30% for rust to form on iron, letting the part cool in a cabinet with a small heater will also protect it. If you have a temperature of 75°F and 70% RH, you only have to raise the temperature of the same air to 102°F or warmer to get the RH below 30%. Not very warm. This is why the Goldenrod heaters work in a gun safe.
 
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