[tpl77]

I built some hot tanks 6x 6x 36 using some 10ga steel plate. It's rusty, but not terrible. What do I have to do to the tank that will hold the hot salts? Can it remain rusty or does it need to be sandblasted or something?

[chris allen]

You can give them a good scrubbing with house hold ammonia and rinse throughly, may even want to pressure wash at car wash.Not neccessary to sandblast but go ahead if you feel neccessary.

Make sure to wear proper safety gear , and proper ventalation when blueing!!!It is nasty stuff.

Good luck ,
Chris

[brickeyee]

Do not heat a bluing tank with any other uncoated steel you care about in the vicinity.
It will rust nearby steel like crazy.

[jpcampbell]

don't do it in a aluminum sided building either, my exhaust stack wasn't high enough and it ate the siding and part of the roof over a few weeks.

[Jim K]

And don't forget that bluing salts will dissolve aluminum and lead. Rebluing something like a Colt Commander frame makes the anti-gun folks very happy, and rebluing an old double shotgun with soldered barrels is one way to get two single barrels.

Jim

[tpl77]

...thanks much for all the safety tips. I've been reading all about the procedure for 4-5 months now and I have all the safety equipment. My setup is in a well ventilated area of my barn. When I slide the doors open, I'm basically outside, but covered by a roof. Cross breeze up on this hill where I live is constant. I'm also in a rural area so any fumes will not affect a neighbor. In fact, after living out here for 15 years, I forgot what neighbors are like!!

On the topic of rust on the inside surface of the tank, I intend to just give it a good cleaning and do not intend to sandblast it clean before I start to add the chemicals. If this proves to be a mistake, I'll post everything I did and hopefully someone can advise me further.

Thanks for everyone's input.

[Big Az Al]

If it is not flaking off the rust won't be a problem.

Did you build a float to put on the solution after your done with what you are doing, to keep the bath ready for next use. My dad taught me to add salts when done for the day that way when the bath comes to temp your ready to make metal blue/black, when starting the next time.

After the bath cools, the salts solidify, you need to brake them up before reheating the bath, if you don't, can you say steam explosion? The liquid everywere but were you want it.

Copper or brass kills bluing salts.

If you get red metal, your putting the parts in at to high a temp.

If it is red slime that wash's off, your to cold.

And last but not least........

the surface prep on the metal in the white has more to do with the final product, then the bluing does!

[Big Az Al]

One of the things I was taught growing up around my dad and a couple of other smiths.

get a good thermomiter, and learn what the process is telling you, IE, that differrent, salts may take adjustments on your part to make then work! etc....

The BOOK on bluing or Black Oxide,

was written for a machine shop setting,

this means it was written for doing parts, in batchs that are all the same hardness and temper.

Since guns are assemblies, of parts with differrent tempers at least, and some alot of differrent alloys,

throw that book away. or at least the instructions that call for timing parts, as this is the easist way to get red steel doing gun bluing!

There are a few start points that need to learned temperature wise, there are temps that are to hot for some parts and they will tell you, red steel is screaming thats to hot. repolish and start at a lower temp, things start turning black insted of red! If you get a red slime on the parts this is telling you not hot enough, but as long as you are hot enough and don't get the slime there is no such thing as to cold!

Winchester nickle steel barrels do blue, start at the lowest practical temperature, and let the barrel stay in the bath until it turns black, or you feel the temp is just way to high, that royal purple alot of then come out is just putting them in at to high a temp. for these barrels you need to get your tank to a roling boil at around 250 F, and let it work thru to sometimes as high 315 to 320F, done right they can be as black as they ever came from the factory!