[TheForge] Gun blue finishing

[Andrew Vida]

Widham, Mitchell P. wrote:
> I recently blued a tomahawk head, it came out a little blotchy, almost
> had the look of color case hardening. I was pleased with the results.
> However when I did some chopping with it, the bluing whore off quickly
> on the contact areas.

Cold bluing is substantially more work than hot.

That said, you have to make sure your surfaces are squeaky-clean - no 
dirt, oils, or other surface contaminants.  Different salts work 
differently.  Some work better with hot metal.  Some require the metal 
be boiled in water after application if the solution.

The way to a good blue is repeated applications in most cases, but not 
all.  I have used cold blue that, when applied in a second coat, the 
first is eaten away.  Winchester's Antique Rust Blue is an example of 
this - it contains some nitric acid and that kills existing surfaces.  I 
used it on wrought iron and after boiling in water the result was OK, 
but not really what I wanted in terms of depth.

You need to experiment a bit.