And is it different for rust vs. caustic.

Harmful or non issue.

Many Thanks

HBH

HBH, I don't plug the bore when I rust blue. I have some tapered hardwood plugs that I bought for rust bluing shotgun barrels but when you heat them, the internal pressure blows them out. You do not plug with caustic bluing. The only surfaces that receive a rust blue is those areas that you coat with the solution. You have to be careful at the bore not to get any inside the muzzle, but it is not difficult. I hang them muzzle down in the cabinet. You do have to take the barrels off to rust blue, or at least it is strongly recommended.

Chic

I second Chic. I also have a full hot caustic bluing setup. Plugging the bore is a trip to Hospital ER, as the salts run at about 295 degrees F and are extremely corrosive to human skin & flesh. The hot air explosion resulting from a plugged bore will propel hot salts everywhere!! Before the salts, the parts are in a 180 degree cleaning bath for 30 minutes, then a cold water rinse. Then into the salts for 30 minutes. After the salts, the parts go into a cold rinse, then a 30 minute neutralizing bath, then a 30 minute hot water bath, then to a dipping oil tank for 2 hours. The bluing does not harm the bore, and I run several patches through the bore when assembling the rifle to get the oil and rust film out.

And if you get into a hot bluing setup, I can give you several hints that are not in the books or the Brownells instructions.

Just a reminder to all the gunsmiths, most of whom need no reminder, the caustic bluing solutions are very dangerous in the eye, with just a little drop or splash capable of ruining an eye. Wear goggles that seal out splash when working around the bluing tank and have a good eye wash nearby. Gallons of tapwater from a hose is a good starting point.

Alkali burns in the eye just eat away tissues, and keep on going. An acid splash in the eye is less dangerous than alkali, because the acid pretty much neutralizes itself as it does the damage, then is done or easily flushed out with water. Not so lye or the similar bluing salts.

I saw one unfortunate fellow after his eye was ruined by a bluing tank.

Avoid anything that could cause a splash and wear those goggles!

Chic & John,

Thank you for the replies. I'm the consumer on this issue. I was just wondering, as just the other day I was told of a fella that lost an eye when a plug let go. I can not remember the name and it was not a recent event.

Many Thanks

HBH

Yup, the goggles, face mask and rubber gloves are standard issue when I am running the tanks. Most gents get into trouble when adding water to the hot salts to maintain the temperature and bath level. There are a few tricks to doing this to avoid splashing, as the water flashes into steam immediately (remember, the salts are at 295 degrees and water boils at 212 degrees).

My bluing setup is in a shed attached to the back of the shop, with three sides open for good ventilation. Ample running water is at hand, and I keep a garden hose set up with a spray nozzle within easy reach of the tanks, just in case of a splash.

My rule when I am bluing: NO spectators allowed!!! Just too dangerous for the unknowning.

Rust bluing sure is a lot easier, it just takes longer.

There was an interesting post on the same topic from Seven Dodd Hughes. He says he uses the tapered hardwood plugs when "rusting" and a rubber one when boiling. He also says he applies a stock finish before starting to the bore and then dissolves it with lacquer thinner at the end. Interesting. I will explore it with him privately. Wondering where he got the rubber plugs.

Chic