"Bluing" is the passivation of the surface to black iron oxide (Fe3O4)

"Parkerizing" is a conversion coating involving zinc or manganese phosphate

In aviation bluing is like the surface oxidation layer of aluminum whereas parkerizing is like alodinde or some other hexavalent chromium conversion.

Thanks Jr. That's really Interesting. I didn't really understand Parkerizing and thought it was just a paint or epoxy finish.

Here's a quick comparison of some finishes I have on hand. The top 2 are just for reference.

Top to bottom
CZ83 with a painted black slide (1994)
FN Hi Power with a polished blued slide (1951)
Glock 19 Gen 2 with black oxide finish (well worn) (1994)
Walther P1 with parkerized finish (1962)

http://forums.pelicanparts.com/uploa...1469605236.jpg

Bluing, by the nature of black iron oxide, starts a thin layer that appears blue but can be incrementally darker. "Black oxide" finish is chemically the same but is actually primarily used as an industrial finish for stuff such as socket head screws. You can think of it as a thick coating of bluing. Parkerizing comes in a few shades of mostly gray with some greens depending on a lot of factors. It would be hard to call a dark blue "parkerized". There is really no difference between a "black oxide" and a matte dark bluing. The matte look comes from using some kind of abrasive treatment such as bead blasting.

A blued gun is a thing of beauty. I've got a vintage Python and the bluing is actually on the blue side. But it's almost too nice to shoot. All of my shootin' guns are either stainless, hard chromed, or have some other coating applied for durability. When you shoot competitively, you tend to clean your guns only when they need it and not after each outing.

Thanks for setting me straight - I clearly had that all wrong.

Now you have me wondering... My M1A is without a doubt parkerized, and I'm pretty darn sure my Springfield 1911 is as well - they are the same dull matte green. Is it possible for parkerizing to come out black, I mean dead flat black, with no hint of grey or green? That's what my new Colt is - could it be just matte bluing? The texture seems identical to parkerizing. Hmmm...

A friend of mine had a beautiful Colt Commander with a blued finish - actually had a blue tint to it. Can a competent gunsmith recreate a like finish? Should you ask to see some of his other finished work?