HOT Blueing question

Nick E

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Hello, my question is what is hot blueing?, and what do I need to start doing it myself? I would appreciate anyones help on the subject. Thanks:confused:
 
It's bluing done with chemicals(there are some acids involved) in a series of temperature controlled vats/tubs. It's not exactly cheap to set up and it requires a room that has no ferrous metals in the room that you don't want rusted. The chemicals get into the air and will leave a light coat of rust on any ferrous metals in the room.
The actual bluing part isn't a big deal, other than controlling the temperatures, but the quality of the finish depends entirely on the pre-bluing polishing. The polishing is the important part. It has to be done so the finish is smooth and doesn't have any edges rounded off.
So you need a room, the vats with temperature controlled heating and a prep room with buffing wheels. Plus the chemicals.
 
If you set up to do it yourself, have all the safety iems, heavy gloves, apron, face protection. The bluing salts in boiling water reach temperatures of over 315 dgrees fahrenheit.Don't use this method on old sxs's because of the soft solder that holds the rib in place ,could melt.As staed above, when your good to go you will have a fairly large investment .Brownells has a 41 piece hot bluing kit complete for $1999.97 american.
 
Or, you can set it up yourself for less than a hundred bucks. :)

I welded up a tank out of a piece of six inch channel.
I bought some Ammonium Nitrate fertilizer,(Not from urea) and some lye.
I used a couple of Coleman stoves for heat.

Suspended the barrel, and other parts on wires in the tank, and worked outside.

Mega Ammonia fumes.
Takes quite a long time to get the temp up to 300 + degrees, and for the piece I was doing, I didn't bother polishing.
The results are black rather than blue, and quite tough.

Sorry I don't have access to the exact mix at the moment, but there are dozens of different formulations.

The top rifle is an un-refinished 1949 vintage '94 Winchester. The bottom rifle a 1914 vintage 1892, is one that was done with the system above.

13589DSC00021.JPG
 
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The bluing salts in boiling water reach temperatures of over 315 dgrees fahrenheit.Don't use this method on old sxs's because of the soft solder that holds the rib in place ,could melt.

Actually the solder will not melt ... it is the action of the salts on the soft solder - the exposed soft solder is eaten away and the remaining salts that are trapped under the ribs attaching the barrels keep on eating and eventually the barrels fall apart. Before all this happens, if the barrels are solidly attached with soft solder, heating them in the salts may blow out the trapped air... like a small explosion of 300 degree caustic soda...
 
An alternative to hot bluing is 'slow rust bluing'

It's safe - no boiling chemicals, just water.

It gives a very tough, attractive finish.

It's cheap monetarily but not in time.:)

KimsMauser98002.jpg


There have been a few threads in the Gunsmithing forum. Do an advanced search using 'rust' as a key word and 'Mauser98' as a User Name.

A Google search will turn up a lot of information.

http://www.canadiangunnutz.com/forum/showthread.php?t=185377&highlight=rust
 
Actually the solder will not melt ... it is the action of the salts on the soft solder - the exposed soft solder is eaten away and the remaining salts that are trapped under the ribs attaching the barrels keep on eating and eventually the barrels fall apart. Before all this happens, if the barrels are solidly attached with soft solder, heating them in the salts may blow out the trapped air... like a small explosion of 300 degree caustic soda...

Right. I stand corrected. Rust bluing takes longer but it might be an easier process over hot bluing, or at least a little less risky.
 
I've been looking at it a lot recently. IMO I think slow rust blueing is the way to go. Cheap, easy, reasonably safe and the chemicals are easy to source and dispose of. The finish is supposedly superior to hot blueing.

For a home project, it's my choice.
 
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