View Full Version : black oxide coating
09-29-2003, 10:32 AM
has anyone had any experience with black oxide coating on steel parts? Any information is appreciated.
Thanks in advance.
09-29-2003, 11:05 AM
We build several hundred M1 Garand rifles a while back from parts and used a variety of finishes, one of which was black oxide. We had a local plating shop do it and the quality varied. Somtimes it came off like paint others it wore quite well and looked good.
I am not sure if you looking to do it yourself or what sort of info your looking for. There are a number of processes that are quite doable in the small shop depending on the volume of work.
09-29-2003, 11:22 AM
I'm not an expert on this, but if you are considering one of the inexpensive do-it-yourself black oxide kits, you should know that there is a difference in quality between the commercial BO and the home kit BO. The kit I have produces a black oxide that rubs off after a short period of time. It's better than nothing but not as good as the real thing.
There was a thread on this a while ago; you may want to check back in the archive.
The process is basically a variant of gun blueing, you just end up with a different oxide that's black instead of dark blue. There is "hot blueing" and "cold blueing." The hot blueing involves some pretty caustic chemicals and, while is can be done at home (see www.brownells.com (http://www.brownells.com) for the chemicals and instructions), it's quite a production and hardly worth it unless you're REALLY serious about doing a lot of pieces.
The cold blueing (or cold black oxide) is another matter entirely, and quite easy. As per GM69camaro, it's not as durable as the hot process, but it's a heck of a lot easier. You can buy black oxide kits from places like MSC www.mscdirect (http://www.mscdirect) or Travers www.travers.com (http://www.travers.com) or any of the large industrial suppliers; just swab the solution on, then wipe and wash it off. Or get a bottle of cold gun blue (Brownell's sells it, or a gun shop should have it) and use that.
The amount of surface prep you do has a bearing on how well it works, and the kind of steel also has a bearing on how well it works. Ledloy (12L14) blues up amazingly well, for instance.
I use some touch-up cold blue from Brownell's, and I'm quite satisfied with the results I get.
Oh -- if you do it, don't put a used swab (or rag) back in the bottle of blueing; always use a clean swab each time you dip into the bottle.
09-29-2003, 11:48 PM
I use the tool black all the time in auto restorations. It works fairly well depending on the metal and finish. If you can give the item a frosted finish, it will work very well. I re-blacken bolts after bead blasting or etching in Phosphoric acid. I've also used it to restore some old tools and make others.
I think I paid 30-something bucks for a quart of it from Enco (It was on sale at the time). Don't bother with the kit. Just make sure your item is clean and oil free. (including finger prints) It works just like the cold blueing for guns. You can buff it with fine steel wool and do it over and over until you have the darkness you want. For steel like W1 drill rod, it takes about 2-3 dip cycles but that is BLACK. Also, that was after it was hardened.
10-01-2003, 07:48 AM
I had one of my 1911's finished in black oxide rather than bluing about 10 years ago and it has held up very well. I believe it is a very good finish for firearms, if you bead blast first you get a very nice matte finish.