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how to do black oxide at home? Answered

 I have some machined steel parts I would like to black oxide to prevent rust and to make look nice. I would like to know the chemicals involved to make the immersion bath for room temperature black oxide.


Best way to get a blacked finish on steel is FeCl3 otherwise know as Ferric Chloride. All you are doing is etching the surface to hold oil on the surface .

heat it up to cherry then cover it in oil. any oil will do but linseed is best. Either put some on a rag and wipe it on when its hot or dunk it in oil. it has to be cherry not any hotter or it will harden and not work


5 years ago

I wouldn't recommend using black oxide because I don't think it would help that much for a long time. Why don't you just paint it with black colour or use black water proof marker.

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6 years ago

for they small parts use a black waterproof marker

Just remember black oxide will only prevent rust for a short while. If you want to keep your projects from permanetly rusting you need to paint or powder coat it.


black oxide turns to rust when exposed to water but it is very porous and adhesive... in history it was used to protect the steel along with oil

After reading that I think I'd just blue it like a gun barrel.

That was my first thought for an answer. But then I thought "maybe this / these is/are big, and gun-blue might be an expensive option, so I'll do a quick one (search) for the question they asked."


If you're in the UK, most engineer's merchants can supply KoldBlak, which is the proprietary process.

I really don't advise making your own.