Hot oil bluing
- Thread starter adosland
- Start date
- Location
- Western Manitoba
Not sure if I had heard it called that? I have heard of "flame bluing" - like on screw heads, etc. - usually something small - polish first - shiny - heat - metal will go through colour changes - dark blue occurs about 590 degrees F. Not certain if that is hot enough to require a quench, but I do not know that... I have a pre-WWI mauser, so more than 100 years old - some parts (bolt stop spring) have noticeable bright blue colour - I assumed that had been accomplished by flame bluing - still quite striking after 100 or more years. Does not see much for handling wear, though...
It really isn't hot oil bluing... hot oil does not impart blue to steel.
Flame bluing is as described above in post 3.
Polish the metal very smooth and bright... heat slowly and carefully with a flame... the first colour to appear will be a light straw... now be careful as too much heat will run through the colours too fast to retain what you may want... light straw will go to a darker brown and then light blue/purples will appear... I like to stop at a nice blue by removing the heat source, but if you have had a bit too much heat there the colours will continue to change... so you could dip in in oil to lower the temperature and stop the colour change. Perhaps this is how you refer to it as hot oil bluing?
The best way to try this is with a steel screw head... prepare it and then heat it and see how the colours change... re polish and do it a few times...
"blue" done this way is not very durable. It looks good on screw heads though.
Flame bluing is as described above in post 3.
Polish the metal very smooth and bright... heat slowly and carefully with a flame... the first colour to appear will be a light straw... now be careful as too much heat will run through the colours too fast to retain what you may want... light straw will go to a darker brown and then light blue/purples will appear... I like to stop at a nice blue by removing the heat source, but if you have had a bit too much heat there the colours will continue to change... so you could dip in in oil to lower the temperature and stop the colour change. Perhaps this is how you refer to it as hot oil bluing?
The best way to try this is with a steel screw head... prepare it and then heat it and see how the colours change... re polish and do it a few times...
"blue" done this way is not very durable. It looks good on screw heads though.
- Location
- Western Manitoba
If you are going to do a whole receiver, I would think you would want to do a bit of experimenting, first - virtually impossible to get the whole thing to same temp with a flame. I was wondering if something like a bath - perhaps a salt bath like used for some metal annealing, might work - it is the heat that makes the colours, I am told, not the flame of the torch. A salts bath at 590 F would have the advantage of not getting any hotter - so entire piece would go to same temperature, so likely same colour, if all previously polished the same?? I do not know, never tried it that way. Have done very small pieces - like pin ends or screw heads - do not know if it can be done with large pieces. And, not terribly durable - should be able to wipe some off with moderate abrasion - comes off totally with steel wool - which real bluing does not. As "home done" alternative, look up rust bluing, or "Express Rust Bluing" - that does work, for sure, but still not as durable as hot bath bluing, I don't think??
Oil bluing does definitely work but at a temp higher than you want to heat a receiver without a laboratory. It behaves something like a carbonia or charcoal bluing. For a Wingmaster receiver, the process would be too hot and unpredictable and you would expose yourself to some very real risk.
The process is distinct from temper color and gives the black iron look of traditional blacksmithing. In my experience it requires a bright orange or hotter steel. It has its place just not on a receiver.
The process is distinct from temper color and gives the black iron look of traditional blacksmithing. In my experience it requires a bright orange or hotter steel. It has its place just not on a receiver.
- Location
- Western Manitoba
I have a chart I copied from old gunsmith book - they used to use the colours as a temperature guide - so brown means 500 F, purple colour means surface about 540 F. Next comes Dark Blue at about 590 F, then Light Blue about 640 F, then Grey-Blue about 700 F. As mentioned - the piece will have heat inside - the colours are about what temperature the surface is at - quit with the heat source, can still get hotter because of residual heat inside - torch flame is much, much hotter than the colour that you are trying to produce. So, needs some experimenting - some practicing - with large or hollow pieces - and then the product is still kind of second or third rate for the use...
few weeks ago I did a demonstration in metallurgy class to compare quenched and tempered steel. they were amazed to see the oxidation color migration toward the point of the center punch to see when it has reached tempering temperature. So if you heat enough to reach oxidization temperature, yes it can affect heat treatmen be careful
I use a nitre bath with a PID controller to keep the temp in a very narrow range.n makes a beautiful blue but it is more durable than temper blue using a torch but less durable than hot bluing or rust bluing.
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Last edited:
fingers284
CGN Ultra frequent flyer
- Location
- Alberta Cowboy Ranges
I can attest to the Grey-blue at 700. I had a Lyman cast bullet sizer still "in the white" when it got a bit gummed up with smeared lead inside, so instead of possibly scratching it up mechanically removing the lead, I just submerged it in a lead melt I had going at the time. The lead melt was at about 700 deg. and at the first quick dunk that sizer turned dark blue but it wasn't submerged long enough to melt the lead off of it so back it went in for a long soak to loosen the lead, when removed this time it was the grey-blue that is described in the chart. The logical conclusion is that the first dunk was to quick to reach maximum temp but the second one (Probably 2 minutes or so) did.
