First Try At Hot Bluing

[kvt]

Take the plunge, It is just do it safely, Even the store chemical bluing can be bad for you if not used properly and wearing the proper gloves etc. Also I have never managed to get the store bought stuff to work right for me. Of course this is not that great, or it is just I can see the problems more since I did it.

 

[Navy Chief]

those pieces turned out excellent op. every time i see one of these threads i start reading with great interest, but by the time im done reading i figure i should just use the store bought blueing for safety reasons.

I concur that the parts turned out great, the more I read about this process though the more I like the looks of the caswell plating black oxide kit.

 

[blaser.306]

I have and use the Caswell's black oxide kit and do like the ease and finish it produces. However I am thinking that I am going to give the caustic solution a try, with the hopes of having a higher gloss result.

 

[brino]

Here is a interesting video on blackening using dirty motor oil

Hey buffdan, thanks for the post.
I had never seen knurling with a hand-held tool before. You showed me something new today.

...and I have jugs of old dirty motor oil....

-brino

 

[chips&more]

I also use the lye and potassium nitrate and the results are excellent. I thought I read all safety stuff on this recipe/procedure in this thread and it should be all heeded to. I would like to add that it should be done outside and stand up wind, wear a face shield and have a fire extinguisher next to you…Dave

 

[kvt]

Well did a second try on a piece of flat plate, dId not work this time. Plate was clean, and everything. The only problem was I ran out of propane and had to go get more, So it stopped boiling in the middle of the process, but did not make blue it at all. So I tried to do the bluing like was in the video that was posted, Heat and old oil, But I could never get an even look to it, Boy did it stink, Used oil burning in the open like that. Did find one thing, do not put the old oil in something that can melt. The heat of the metal heated up the oil, and even got so hot the oil pan flash fired. I do not like that type of Blackening at least not on a large piece. Just have to figure out why the hot mixture did not work.

 

[benmychree]

The end product looks very nice indeed; my reading of all the comments regarding caustic chemicals only makes my favorite method of bluing and blackening look all the better; this is the U.S. Armory method, and it has lots less problems in that regard; it is simply 50% mixture of sodium nitrate and potassium nitrate with a little manganese dioxide thrown in to "clean" the bath, which is melted and heated to 600 - 650 deg. F., and the articles dipped in for as little as five minutes, depending on the size and color desired. No discernible fumes, no need to clean the work of oil or whatever. After the bluing is satisfactory, the article is quenched in warm water, then into oil for added corrosion protection. the only protection needed is a heavy shirt, gloves, and a face shield to guard against burns. It can be done indoors without worrying about fumes, as with the caustic chemicals. I also use this bath (provided with a pyrometer burner control for close control of temperature) for tempering in heat treating.

 

[benmychree]

Well did a second try on a piece of flat plate, dId not work this time. Plate was clean, and everything. The only problem was I ran out of propane and had to go get more, So it stopped boiling in the middle of the process, but did not make blue it at all. So I tried to do the bluing like was in the video that was posted, Heat and old oil, But I could never get an even look to it, Boy did it stink, Used oil burning in the open like that. Did find one thing, do not put the old oil in something that can melt. The heat of the metal heated up the oil, and even got so hot the oil pan flash fired. I do not like that type of Blackening at least not on a large piece. Just have to figure out why the hot mixture did not work.

I think this is a good reason not to use old used oil, and rather use quenching oil, which has a high flash point.