Nitre bluing step by step.

calebib · January 2015

I was finishing up a rifle build today (which I will start another post about) and I needed to nitre blue a few parts so I thought I take a few pics and show you all the process. It's actually very easy though not without some risk.

The first step is polishing the parts. To be blued today was a steel grip cap, some action screws, bolt stop screw and the bolt stop cover. I wanted a fairly bright finish so I polished them to 600 grit. The screws got spin polished in a drill and the cover and grip cap were hand polished up to 600 then finished up on the buffer.

Sorry for the blurry pics.

Hand polishing.

Buffer polishing.

The parts then get hung from a piece of thin wire and degreased.

The nitre salts are then heated up to between 575 and 650 degrees.

The part is then suspended in the molten salts until the desired color is achieved. You can get a range of colors including the straw color found on Lugers and the like.

The part is then quenched in water. Care must be taken to ensure you don't get any water in the molten salts, that is unless you want a 600 degree mini volcano.

Dry it off and give it a coat of oil and you're done!

Farm Boy Deuce · January 2015

Chemistry is fun.

Big Al1 · January 2015

As with all blue jobs, the prep work is the most important part to achieving the properly finished product. Very interesting and nice job!!

calebib · January 2015

Exactly, two hours of polishing and five minutes to blue.

calebib · January 2015

If you've ever taken apart an old gun and found springs finished in this type of bright blue, the pretty color is just a nice side benefit. After Heat treating a spring it will be brittle. If you nitre blue it and let it air cool, rather than quenching it, this will normalize the steel giving you a usable spring.