Nitre Bluing

[no4mk1t]

Really enjoyed these two Rust/niter threads. Thank you for posting. What type of pot are you using to melt the salts in? I presume it re-solidified as it cooled. Does the solution become weaker as it is reused?

Thanks!
I would encourage those who want to try these 19th Century bluing techniques to do so. Both processes are low tech and simple to do. All the work is in the metal prep.
The pot used in the Nitre thread is a simple cast iron pot. You can use anything that will withstand the 850* temp. I first tried a bread pan. My only mistake was the one I bought was painted black. I assumed the paint was high temp and would be OK. Wrong. If you are going to use a bread pan, get one that is bare steel.

The salts are granulated when you buy them. After you melt them and they cool down, they solidify, but are easily melted again for subsequent uses. There is no solution to weaken as with parkerizing or hot caustic bluing methods. The salts are simply a medium to heat the parts to the required temperature. The heat itself does the bluing. Small parts like pins and screws can be blued in the flame of a propane torch.