Damage Industries has a black oxide and mag phosphate option for many of its small parts.  I understand mag phosphate is parkerizing which i’m familiar with.  Could someone educate me on Black Oxide and wether it’s a better or worse option for the same price?

Black oxide is bluing. There are a few different methods to produce bluing but black oxide is the standard one today. Like nitride, what it actually looks like depends a lot on the final metal finishing. Could be dull, could be shiny, could be blue, could be black. It's not what I would consider one of the better modern finishes but that's your call.

I did reach out to damage industries and CS indicated that it’s nitride/melonite with a black oxide finish.  I assumed it was just the black oxide akin to bluing like you mentioned but I guess not.  Seems like a great deal since it’s the same price as parkerized parts.

I thought black oxide is the finish used for those allen socket head cap screws, which on the engine in my car show rust in no time when exposed to humidity or moisture over time.  also, the standard Desert Eagle is black oxide, which is pretty weak, rubs off in no time to bare metal, which then is vulnerable to rusting.

now, black oxide over something else that provides corrosion resistance or surface protection, that'd be ok.  but black oxide by itself is only cosmetic, not functional or durable.

Yeah, when I saw the label  “black oxide” I was thinking it was going to be a lessor finish. I just received a few small parts with the finish and they look just as good as the nitrided Faxon and Troy small parts I have experience with.

https://www.google.com/search?q=black+oxide+process&newwindow=1&source=lnms&sa=X&ved=0ahUKEwir48bDpfTYAhUUSmMKHemLA5sQ_AUICSgA&biw=1920&bih=974&dpr=1

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Black oxide is what others call melonite, qpq. It's the same thing and it's better and tuffer then chrome. It gas lube properties in it also like nickel. It's alot easier to clean. Way better then park.

AFAIK, in my limited experience, has been that black oxide is not the same as melonite, or salt bath nitriding, or quench-polish-quench.  until this thread, i didn't even know that there were several grades of black oxiding.  I guess my Desert Eagle, and the socket head cap screws on my car have the cheapest version.

I believe the consensus is that black oxide ,akin to bluing, is still a process done on its own.   Some companies choose to melonite and then apply a black oxide finish and then label as straight black oxide.   Why it’s not pimped as melotine as opposed to black oxide is confusing.

The thing that probably threw me the most was the price between parkerizing and melonite with black oxide was the same.  Historically melonite tends to run a few bucks more but in the case of damage industries they are offered at the same price.

It wouldn't make any sense to melonite the parts, then go over that with a black oxide treatment. The melonite is infinitely more durable and also more attractive. If Damage Industries told you they're melonited and then black oxided, I think they were mistaken. Just doesn't make any sense. Imagine taking a beautifully nitrided barrel and then ruining that with a black oxide finish over top. Wouldn't make any sense, would it?

Besides, traditionally, black oxide has been a bluing process, which is a rusting process. I don't think you can even rust melonited parts. They are extremely corrosion resistant.

I could be wrong but I don't think Nitrating is a finish in itself it is just a surface treatment meaning if they wanted to Nitrate something it doesn't mean it comes out that beautiful shiny black you always see.  But everyone adds a finish to it when doing the process which gives it that color.  I am guessing that is Black Oxide?

I could be wrong.. just pretty sure I remember reading that a finish has to be added with the Nitrating when they are doing it to get the blackish color we all see.  Either way I love the look of the gray parkerizing on AR parts and think they contrast well with the black.  I wish sources were more consistent in their coatings, sometimes when I order a FSB it is very gray and other times it is almost black.  Same for port doors.  I think it looks best on the barrel when it is Nitrated black with a light gray parked FSB.

Uh, no.  Black oxide is simply old style hot bluing.  It is controlled rusting.  It provides no surface hardening.

http://www.blackworksusa.com/whatisblackoxide.html

When used in conjunction with QPQ SN nitriding by adding oxidation agents in the hot salt bath (black nitride), the finished product has a deep black satin, almost glossy appearance.

QPQ SN nitriding without an oxidizing agent or dye is virtually colorless.  High performance automotive crankshaft journals that have been nitrided look no different that bare untreated ones - same color as the substrate metal.  Ground enough crankshaft journals over the years to have some familiarity with this.

Sounds right.  If I look at an M&P slide it differs in color from a Glock slide and, just generalizing, the process both slides go through is about the same.   A while ago Glock slides used to be a much darker black, they changed something and  the finish has a lighter grey tint to it.