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Black oxide - how/where?

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owdbob:
Hi ,The October edition of Model Engineers Workshop has an article on "Home Metal Blacking". It has details and a pictorial run through. The supplier mentioned was//Delway Technical Services,192  Seabank Road, New Brighton, Wallasey, Merseyside, L455AG :tel 01516393201.  The author gave his email as " terryowens99@tiscali.co.uk"  I am very new to this hobby to web-forums,so, I hope this information is relevant and that I have not broken any rules.( I should be known as "Bob the bewildered" 

sub-xtx:
Hi guys, sorry for my English. :bang:
You can try to black iron with an old method:
#1 part (i.e. 20grams) of Sodium Hydride
#2 parts (i.e. 40 grams) of Potassium Nitrate
#3 parts (i.e. 60 grams) of water
warm until boiling e put your piece in, let it few minuts checking for your wanted color.
PAY ATTENTION using Sodium Hydride!!!!!!! It's very caustic.
Protect yourself with gloves, eye-glasses,etc.
Good luck.
Osvaldo

rleete:
I recently tried a method I read about here or another forum.  Take your part, and heat it with a torch (I used plain old propane) until it starts to turn blue.  Takes only about a minute.  Then, dunk it into used motor oil (dead dinosaurs, not synthetic!) for a few seconds.  Do this outdoors, it will smoke and stink.  Repeat the heat and dunk  - no color change to guide you, so just heat it until you've burned off all the oil, and then keep going for another 30 seconds or so.  Try to heat it evenly.  Dunk a second time, and swirl it around under the oil.  Comes out looking a nice matt black.  Finish depends on the original surface finish of the part, but I just hit this one with some sandpaper (220 grit?), and it was not buffed or polished.

Here's a pin I made to repair a coworker's airsoft BB gun:

Corvus corax:
It doesn't have to be motor oil. Linseed oil, bees wax, canola oil and peanut oil all work. It's effectively the same method that is used when one seasons a wok or skillet.

You can either paint the oil on first and then heat it or heat it first doesn't matter.

The part doesn't have to be heated till red hot and then quenched. One just needs it hot enough to open the pores of the metal.

Linseed oil was the traditional method to protect wrought iron. Some smiths also mixed Linseed oil and Bees wax.
I 've done small firearm parts with Linseed oil and they came out looking pretty good. Just repeat multiple times to deepen the colour.

As to the cold blues: Birchwood Casey "Super Blue" works well.
A couple of years back I stripped down an old Enfield No1 and reblued it completely with that stuff.
It came out very nicely. The finish isn't quite as hard wearing as a proper rust blue or for that matter the aforementioned oil blackening.

Just don't use it on surfaces that will see a lot of wear. I recently blued a rest for my offhand grinder with it and while it works better than other cold blues it is rubbing off.

bry1975:
Any of you chaps send out parts to be PVD or DLC'D?  you know like the drill bit coatings.

Bry

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