[VAC] Re: Blackened metal

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxx>]

There's the rust reclaimer black, I don't know how it stands up to
anything, then there's strong gun blue. Classic gun blue color was
accomplished by heat, but there's a chemical type that is blacker, likes
to have a bit of oil applied afterwards to make it blacker. Its found in
gun shops and gun departments, there are several brands. I've used it on
hand made machine tools and its lasted very well.

Gerald J.