Hot Bluing

I've watched many You Tubes and read articles about hot bluing. All of them involve water in some way or another. Either steam or immersion and boiling. I'm curious about the bores and chambers. How do you keep the inside of the bore from rusting during the process?

I think your asking about rust blueing, hot blueing is done in caustic salts at nearly 300 degrees. So in rust blueing ,yes the bore is protected in some way. The bore can even be coated with shellac then cleaned out with alcohol.

Phil Coffins said:

I think your asking about rust blueing, hot blueing is done in caustic salts at nearly 300 degrees. So in rust blueing ,yes the bore is protected in some way. The bore can even be coated with shellac then cleaned out with alcohol.

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I’ve used lacquer to temporary coat and protect the bore when rust bluing or browning.

When I rust blue a barrel I will plug the bore at the muzzle and leave the breach plug in. The vent will be plugged or drilled at a later date. When the rust bluing is done I remove the breach plug and rinse the barrel off inside and out with clean water then dry it thoroughly. I then oil the outside and inside. The barrel is now ready for the next step of the build.

Thank you. Yes, rust bluing. Doesn't the heat of the steam or boil cause the lacquer or shellac to separate? I've had lacquer finished cabinets next to a bathroom fan heater before and the heat bubbled and ruined the finish on them.

And, (relatedly) don't you worry about the plugs leaking or the liquid seeping under at least a little bit of them too? The thought of a wine cork pulled from a bottle springs to mind. There is always a little wine that has seeped past the end of it and is permeating the cork. With the heat of the boil or steam going on the parts are going to expand and change the seal characteristics too.

I can't answer this part of your question because I don't use lacquer or shellac on my parts -- "Thank you. Yes, rust bluing. Doesn't the heat of the steam or boil cause the lacquer or shellac to separate? I've had lacquer finished cabinets next to a bathroom fan heater before and the heat bubbled and ruined the finish on them. "

But I can answer this -"And, (relatedly) don't you worry about the plugs leaking or the liquid seeping under at least a little bit of them too? The thought of a wine cork pulled from a bottle springs to mind. There is always a little wine that has seeped past the end of it and is permeating the cork. With the heat of the boil or steam going on the parts are going to expand and change the seal characteristics too. "

Yes - the plug in the muzzle and vent does leak as I can see bubbles coming out but it does not do any harm if you wash and dry the barrel thoroughly just as if you were cleaning your rifle after a day at the range shooting it.

I've done this a bunch of times. Just oil the bore well , drive in a wooden dowel and plug the touchhole with a toothpick. When you take it out of the boiling water it dries almost instantly. Never had the bore rust.

In a commercial blue shop we plugged muzzle and breech end to rust blue. Wood plug dipped in urethane Removed after process. Some barrels we had threaded rods and rubber plugs for was quick but some bores it was easier to use the wood plugs.

DO NOT plug bores in hot caustic bluing.