Posted by Mike DeHart on December 18, 00 (from the WWWMachine Shop forum) Hello, all,

How do I put a black oxide finish on small steel parts? I am just a hobbyist working at home. I seem to remember something about boiling small parts, but I don't remember if that was a surface finish or something else. Thanks for any help you can offer.

md...eyes open, ready to learn.

Posted by John Lawson
In Reply to: Black oxide finish? posted by Mike DeHart

Here's how I do it: Boil the parts you want to finish after rinsing them with hot water and dishwashing detergent. Add a small amount of baking soda to the boining vessel. Then change the water and boil the parts again. If ;you can use distilled water, so much the better. (If you skimp or skip these important cleaning steps, your finish will be pisly and mottled.)
Remove the parts from the boiling water and dry them on a piece of folded newspaper. Apply your black oxide solution (sold by gun shops or gunsmith supply houses like Brownells. Oxpho Blue, Dichro pan T-4 or Birchwood-Casey black all work well.) Several other brands of blueing solution will work also. Leave the water at a boil. When coated, replace parts in the boiling water for 20 minutes. Remove parts, dry on newspaper,, apply finish coat of blueing solution with a piece of cotton. Rub well with a soft cloth. Dab on a coat of linseed oil, but only leave it on the parts for one hour. Replace linseed oil with Vaseline petroleum jelly by rubbing it in well with a soft cloth.
This will give you a finish equal to any tank blue. If you skip any steps or just smear on the blueing solution, you will not have a professional looking finish. It is the technique used in application that counts. If you want a maintenance-free surface, remove the Vaseline after several days and apply a coat of silicone auto wax. Lasts for years in normal use.