Diy hot blueing

[MJP]

So had a go on hot blueing DIY, there is nothing special to it.
Just lye distilled water and some natriumnitrate.
Had some .257 upper parts machined ready that needed blueing, and I have blued some parts before.
Recipe: pour 1 liter distilled water (battery water) in to a pot.
Turn on the hot plate, low heat, add lye 600g stirring slowly.
Turn up the heat and bring the solution to a boiling point, add nitrate 200g
Add prepped parts, on what ever surface finish you desire degreased, suspended somehow with stainless suspenders.
Keep the solution boiling moderately and wait for a colour to turn black.
Ready.


Edit, almost forgot to mention, be sure to rinse the parts after the blueing bath, and wear protective clothing and eye protection. I take no responsibility if someone tries this method and gets hurt, try it at your own risk, this stuff is caustic and the fumes toxic so proper safety measures must be taken.
And use stainless steel for your pot and stirring stick.
Oil the parts well preferably leave them in an oil bath for a day.

Marko

[David.Soliman]

I've used the same recipe you mentioned before and experimented with it a lot, it seems to be temperature sensitive, giving the best results when the solution reaches a temperature 160-180 Celsius, the solution will reach this temperature only if it was super saturated.

It's worth mentioning that this method gives a very nice and even dark black color and a lot more consistent than cold bluing.

[MJP]

Yeah I have noticed that too, but when it's just right it's very fast reaction, normal 52 steel blues almost instantly only takes minute or two to get dark grey.
And black is around 10min.

Marko

[StevenG]

Just to make it easier for Americans, natrium is sodium.

You did it right, but it might be good to remind folks to always add the lye to the water, never the other way around.

Looks awesome, by the way.

[MJP]

Oops, yes sodium, silly me. And true always lye in to water and slowly. If you don't know what you are doing with caustic chemicals, don't do it.
Thanks for your comment.

Marko

[sr1sws]

And do NOT use an aluminum container!

[MJP]

Good call, only stainless or enamel are good, don't know about regular iron or steel pots, but stainless is a sure bet. And the solution can be stored in a plastic container with a lid on it.

Marko

[Gippeto]

Hot bluing is something I've been wanting to have a go at for some time...I HATE cold blue with a passion.

When I do give it a try, this is what I'll be trying;

http://bbs.homeshopmachinist.net/threads/41492-Backyard-hot-caustic-bluing

Have been doing some rust bluing though....a LOT less dangerous than hot bluing, but there's a good reason it's called SLOW rust bluing.

Parts for a Crosman 100...rust blued with a solution made from hydrogen peroxide, white vinegar and sea salt.



Al