Those of you who read my builds know that I like the look of blued steel on my models. I have used many cold blueing products with somewhat inconsistent results. I was talking to a friend of mine who does gun smithing about blueing and he recommended just hot blueing the parts. He told me that the Niter salts melt in the same temperature range as Lead. This post will document my attempt to use the method he recommended. Let's get started. I happened to have a unused lead pot from my muzzleloading days. So I decided to use it for this experiment.
I bought a tub of the recommended blueing salts from Brownells.
This is what the salts look like.
I poured some into the pot and started it up.
A couple of things to note here. As the salts melt the level will go down. I had to top up the pot with salts a couple of times to get to a useful depth of salts. It took about 30 min for the salts to melt and go translucent.
Next it was time to blue the parts. My friend uses the basket from an old home fryer to dip his parts. That wasn't an option for me so I used some iron wire and suspended them from a length of threaded rod.
A couple things to note. When you first dip the part salt will crystallize on it because it's cooler then the salt. Just swish it around until it's clear. That's your clue that the part is almost up to temperature. Now all you have to do is watch it. When it gets to the color you want quench the part in water. When the part is cool pull it out and spray it with water displacing oil to keep it from rusting. The finish is still soft at this point so I spray the part with gun oil and let it sit overnight to firm up. Here are the results.
Let's talk about surface prep for a moment. For a matte finish rub down the part with 200 grit paper. For a reflective finish polish the part to a shine. In both cases clean and degrease the part prior to blueing. For safety reasons make sure the part is completely dry prior to dunking into the salt. Any liquid would turn to steam and could splash hot salt on you.
PPE for this task is gloves, face shield and an apron. Do this in a well ventilated area.
I hope this is of use to some of you.
Tony