Rust bluing, temperature and humidity

Olle · 04-26-2010, 09:30 AM

New member here, working on old guns as a hobby and a side business. No Luger yet, but planning to get one as soon as "the right one" shows up...

I have had good luck restoring old firearms using the slow rust method, but I'm still experimenting with it to get a more controlled process. My shop is in the basement where the humidity and temperature can vary quite a bit, so this weekend I built a temperature controlled cabinet. I haven't tried to rust anything yet, but a few test runs show that I can maintain a given temperature quite well. The humidity control is still on the drawing board, so until I can get a humidifier installed I'll just use a hot pan of water, spray bottle or whatever it takes to get the right humidity.

My first question is what the ideal temperature and humidity would be. I usually use Pilkington or Brownells, and they both seem to work quite well under average shop conditions (65-70F, 45-50% RH). It's still a bit of a hit-or-miss proposition, and I assume that raising the temperature and humidity to a constant level would give me more consistent and predictable results. The few brief test runs show that I can get at least 90F in the cabinet, but I will need to experiment a bit to find out what the max humidity can be.

The second question is how to achieve the right color. I usually get a graphite black, sometimes with a slightly blue tint to it. It seems like the color depends on the type of steel rather than the method used, but I figure that there would be a way to get this blue color on any kind of steel given the right rusting solution and temperature/humidity conditions. I have searched the forum, and I get the impression that this is a well guarded secret, but I'm still hoping that someone can lead me in the right direction.

Any advice will be appreciated!

04-26-2010, 09:30 AM	#1
Olle User Join Date: Feb 2010 Location: Tennessee Posts: 1,149 Thanks: 159 Thanked 664 Times in 318 Posts	Rust bluing, temperature and humidity New member here, working on old guns as a hobby and a side business. No Luger yet, but planning to get one as soon as "the right one" shows up... I have had good luck restoring old firearms using the slow rust method, but I'm still experimenting with it to get a more controlled process. My shop is in the basement where the humidity and temperature can vary quite a bit, so this weekend I built a temperature controlled cabinet. I haven't tried to rust anything yet, but a few test runs show that I can maintain a given temperature quite well. The humidity control is still on the drawing board, so until I can get a humidifier installed I'll just use a hot pan of water, spray bottle or whatever it takes to get the right humidity. My first question is what the ideal temperature and humidity would be. I usually use Pilkington or Brownells, and they both seem to work quite well under average shop conditions (65-70F, 45-50% RH). It's still a bit of a hit-or-miss proposition, and I assume that raising the temperature and humidity to a constant level would give me more consistent and predictable results. The few brief test runs show that I can get at least 90F in the cabinet, but I will need to experiment a bit to find out what the max humidity can be. The second question is how to achieve the right color. I usually get a graphite black, sometimes with a slightly blue tint to it. It seems like the color depends on the type of steel rather than the method used, but I figure that there would be a way to get this blue color on any kind of steel given the right rusting solution and temperature/humidity conditions. I have searched the forum, and I get the impression that this is a well guarded secret, but I'm still hoping that someone can lead me in the right direction. Any advice will be appreciated!