fire blueing

[Gemoke]

Can anyone tell me how fire blueing is done. I would like to do some screws on an old gun that I have and was wondering how to go about it.
cut finger

 

[paulvallandigham]

First polish the screwheads until they are in the white. Then heat them up slowly with a torch, or gorge until they turn blue in color. Then quench them in oil to set the color. I have used a spray can of WD40 in the past to simply spray the screwheads to cool them and set the color. The blue is a nice color, but I don't find it as durable as other methods.

 

[tom hargrove]

does wd-40 have a low flash point?

 

[k.jacobfrost]

does wd-40 have a low flash point?

I would say it does. It lites up nicely when a lighter it held up to the stream.

 

[paulvallandigham]

I don't know that the oil has a low flashpoint, but whatever is being used to provide the gas to spay the oil out of the can certainly is flamable. I have not had any problem with the WD40 oil flaming up spraying it on the heated screws. Perhaps I have not reached the flashpoint of either the oil, or the gas in the spray. Or, perhaps, the spray itself snuffs out, and cools the screwheads down so quickly, that neither the oil or the gas in the spray can be ignited. Just don't hold a match to that spray, unless you want a hand held torch or flame thrower.