Rinsing after bluing

[brian10x]

I'm getting ready to blue a handgun using potassium nitrate. I've done it before, about ten years ago, and I'm giving it another go.

After the parts get to the desired shade of blue, I was going to dip in water to stop the process and rinse off the salts. However, I'm a little concerned that going from such a high temperature to a cool water rinse could result in metal warpage.
Maybe I should dip the parts in hot water instead?
What have been your experiences?
Thanks for the advice!
Brian in Tucson

 

[BigTub]

Note I have no specific experience in this operation.

What temperature for the bluing? Molten salt bath? Warping occurs due to temperature gradients. It certainly would not hurt using the hot water but immersion in a big pot with stirring would be better than a spray, for example, at keeping the gradients to a minimum. Hot water also is better at dissolving salts. I would not soak it very long as some coatings are somewhat water soluble. The hot water exit condition would also aid in drying and help to set the color. Be sure and blow all the water off and minimize handling for a while.

 

[brian10x]

I plan on bluing around 520 degrees for a purplish-blue finish. I think I agree. I'll plan on immersing the parts in a hot water bath to hopefully eliminate any warpage.

 

[needsmostuff]

Does the rinsing have to be don straight out of the bluing tank?
Or could you air cool it for a couple of minutes.
Out of the tank the temp will fall fast.

 

[brian10x]

I think air drying might solidify the rust. I think it needs to be rinsed right away.