Has anyone here used black oxide as a finish? Our company uses a local place for this and it looks great on our parts. Very black and carries whatever polish level the part has before it's done. The owner of the B/O co says it is in fact the same process as bluing. They do Smith & Wesson parts for Smith. He claims there is no change dimensionally and the bore is not affected other than color. Plugging does not work and they don't want any coatings in the bore that would contaminate their chemistry. I can get this done easily and if I wait, no paper.

Black oxide is the same thing as caustic or rust blue. It refers to the magnetite form of iron that is formed on the surface of the steel/iron part.

All of the older Herters parts that were "Blued" such as "poly chokes" and many many other parts were commercially black oxided.

IMO it's the same as gun metal bluing but possibly a slightly different formula.

It may be a slightly different formula but what you end up with chemically on the gun is the same thing. But keep in mind that a Black oxide service may not have any experience with guns. (the company you mention excluded) So be sure the part is finished the way you want BEFORE you send it off to them. And Blueing covers up NOTHING when it comes to lack of polish or mistakes.

I would assume you know that but some reading this may not.

no relationshio to hot blue .. i tried 3 different kits and setups .. nothing like hot or rust blue .. better than cold blue maybe .. NOT worth my effort ...

Bluing (steel)
From Wikipedia, the free encyclopedia


Bluing is a passivation process in which steel is partially protected against rust, and is named after the blue-black appearance of the resulting protective finish. True gun bluing is an electrochemical conversion coating resulting from an oxidizing chemical reaction with iron on the surface selectively forming magnetite (Fe3O4), the black oxide of iron, which occupies the same volume as metallic iron. Black oxide provides minimal protection against corrosion, unless also treated with a water-displacing oil to reduce wetting and galvanic action.

Hot black oxide

A hot bath of sodium hydroxide, nitrates, and nitrites,[5] at 285 °F (141 °C),[6] are used to convert the surface of the material into magnetite (Fe3O4).[3] Water must be periodically added to the bath, with proper controls to prevent a steam explosion. Explosion of these caustic baths has repeatedly claimed lives, making this a dangerous process.

black oxide parts treatment is room temp or warm .. NOT hot salt bathes ...

quote:

Originally posted by jeffeosso:
black oxide parts treatment is room temp or warm .. NOT hot salt bathes ...

While there is a chemical process on the market that will Black Oxide at room temp. The commercial black oxide process is in fact the same as Traditional Hot bluing salts

quote:

Originally posted by kcstott:

quote:

Originally posted by jeffeosso:
black oxide parts treatment is room temp or warm .. NOT hot salt bathes ...

While there is a chemical process on the market that will Black Oxide at room temp. The commercial black oxide process is in fact the same as Traditional Hot bluing salts

no disrespect intended ... and you may certainly be right.. walnut might be using a caustic company and not knowing it ..

i did a long bit of research on this a couple years ago, at the request of ar members wanting to know about black oxide room temp ..

http://www.caswellplating.com/kits/black.htm
its on of many commerical ops .. the finish is horrid

i also talked with several engineers and back tracked to the makers .. NO BLACK OXIDE "kit" produced anything like caustic blue .. as all of these guys are on the market to produce a black oxide finish that is not so nasty to the user or hazardous to INSURANCE ....

at least it doesn't stink like cold blue.

i also did some talking to birchwoodcasey about their approach.. as well as their greying .. there's no more cost effective way to blacken firearms than caustic blue.

simple test

Walnut -- does your process take place near 300degrees f?

quote:

Originally posted by jeffeosso:

quote:

Originally posted by kcstott:

quote:

Originally posted by jeffeosso:
black oxide parts treatment is room temp or warm .. NOT hot salt bathes ...

While there is a chemical process on the market that will Black Oxide at room temp. The commercial black oxide process is in fact the same as Traditional Hot bluing salts

no disrespect intended ... and you may certainly be right.. walnut might be using a caustic company and not knowing it ..

i did a long bit of research on this a couple years ago, at the request of ar members wanting to know about black oxide room temp ..

http://www.caswellplating.com/kits/black.htm
its on of many commerical ops .. the finish is horrid

i also talked with several engineers and back tracked to the makers .. NO BLACK OXIDE "kit" produced anything like caustic blue .. as all of these guys are on the market to produce a black oxide finish that is not so nasty to the user or hazardous to INSURANCE ....

at least it doesn't stink like cold blue.

i also did some talking to birchwoodcasey about their approach.. as well as their greying .. there's no more cost effective way to blacken firearms than caustic blue.

simple test

Walnut -- does your process take place near 300degrees f?

Jeff
We are on the same page here.

When I say "Black oxide" I mean Hot caustic salts. Same as hot bluing.

We have a shop here in southern California and they advertise as a black oxide service. I've sent them surface ground parts and they come back just the same as a gunsmith would do.

I think the miscommunication is in the term "Black Oxide" and some tend to believe this is cold blue or room temp stuff.

A true Black Oxide is magnetite just as is Hot blue.

And yes the room temp stuff is garbage at best. eeven the Caswell stuff is garbage.

quote:

Originally posted by jeffeosso:

quote:

Originally posted by kcstott:

quote:

Originally posted by jeffeosso:
black oxide parts treatment is room temp or warm .. NOT hot salt bathes ...

While there is a chemical process on the market that will Black Oxide at room temp. The commercial black oxide process is in fact the same as Traditional Hot bluing salts

no disrespect intended ... and you may certainly be right.. walnut might be using a caustic company and not knowing it ..

i did a long bit of research on this a couple years ago, at the request of ar members wanting to know about black oxide room temp ..

http://www.caswellplating.com/kits/black.htm
its on of many commerical ops .. the finish is horrid

i also talked with several engineers and back tracked to the makers .. NO BLACK OXIDE "kit" produced anything like caustic blue .. as all of these guys are on the market to produce a black oxide finish that is not so nasty to the user or hazardous to INSURANCE ....

at least it doesn't stink like cold blue.

i also did some talking to birchwoodcasey about their approach.. as well as their greying .. there's no more cost effective way to blacken firearms than caustic blue.

simple test

Walnut -- does your process take place near 300degrees f?

Thanks for the input guys. I'm going to discuss their process in more detail. Today if I get time. I usually speak with the owner of the company and he's a great guy. He'll tell me anything I ask.
Just curious - no one mentioned anything about the affect it may have on the bore accuracy wise. My guess is none assuming it's similar to hot blue. I also assume factories blue after rifling.

I just got off the phone with the VP of the BO company. Bobsters description "A hot bath of sodium hydroxide, nitrates, and nitrites,[5] at 285 °F (141 °C),[6] are used to convert the surface of the material into magnetite (Fe3O4).[3]" is exactly what they do. According to them, the room temperature kits have been around awhile, but mainly for tool room fixtures and other captive work. It does well on materials like ductile iron as they are tough to convert the surface to this magnetite with the hot process.
Yes, the finish gets the bulk of it's protection by keeping a film of oil on it. They offer a water soluble type and a mineral oil base version which is what we specify. While I would prefer a hand rust blue if I were building a custom, there is some attraction to getting this done 20 minutes from my house and probaly get 2 barreled actions done for a 100.00 dollar lot charge.
Walnut

As for accuracy change?????? Well that's opening a can of worm A BIG FRIGGIN CAN OF WORMS.


That said I have never tested to see if there is any difference and I would bet big money that Blueing in the bore if performed correctly will have no effect to improve or worsen accuracy or barrel life.

Now there are some that emphatically believe that anything other then raw steel in the bore will have an effect on accuracy.

so to each his own

But that's like saying one cartridge is more accurate then another based solely on the cartridge. And there are tons that believe that as well.

KC<
you are right, it's hot blue.. thanks for being patient with me

Jeff
No sweat but that's the difference between a process name and a marketed product name. either way it can add to the confusion

Do you want to "go there" with rust brown, rust blue, plumb brown, yada ydad yada.