Hot Oil Bluing?

[mastiffhound]

I was looking at cold blue products when I came across this. I did a search but came up with cold blue and acid based bluing. The cold blue stuff has been reported to not be very wear resistant and I'd rather not screw with acids as I would have to dispose of them. I really liked the look of the parts that were hot oil blued, it reminded me of older Colts that had that deep high sheen. My dad's older Para 1911 has the grip safety showing wear and small specs of rust have begun to develop.

I know to clean and polish but wondered how hot do I need to get it? 500 degrees, 600? I know till the metal is bluish or purple but I'd like an actual temp that is close. Will that be too hot, enough to change the temper? Can I use synthetic oil, Mobil 1? I can't imagine that the grip safety is super hard but more than likely has some temper. It only pushes on a small piece of leaf spring but I want to be sure I won't do any harm.

As always, thanks for the help!

 

[4v50 Gary]

Isn't the burning of motor oil carcinogenic? Suggest you look up Express Bluing. It is more doable at home than hot salt bluing. You need a propane torch, a wire brush and a tank large enough to immerse your workpiece in boiling water.

 

[mastiffhound]

I would be doing this outside, not much to worry about there. I'm looking at heating the part then dipping in oil, not the same as hot salt bluing. I'll be using a torch or even my stove I have in the workshop. The process I'm looking at doing involves heating the part then submerging in an oil, nothing more. I've got 2 cycle, synthetic, dino-based, used syn and dino, gun, linseed, and some other oils I can't remember I'm sure.

Here is a video of the process: https://www.youtube.com/watch?v=N3jt-73JfEE

 

[LAGS]

What you are describing as Hot oil bluing is also known as " Lamping '
It works great on small parts where you can control the heat in the metal and keep it even thru out the part.
It works, and it does tend to last.
But it is not meant to try and Touch up worn parts.
It comes out all Funky colors with Bluing and lamping on the same part.
The tempature will depend on the type of steel, the finish on it , ( polish or blasted ) and the type and weight of oil you use.
Regular oil is best, not Synthetic or Detergent oils.
I use straight 30 weight non detergent oil for small parts that I lamp rather than bluing.
Do not get Slides, Barrels , Frames or cylinders Red Hot.
But small parts like Sights and such are fine and can put a case hardenig on them by Oil Quenching.

 

[rcmodel]

I wouldn't even try it.

What you are suggesting sounds like is to heat a piece of metal till it turns blue, then quenching it in oil to retain the blue color?

First, without knowing the type of steel it is made from?
You have no idea what will come out of the oil.

1. It will either be annealed and softer, if it is heat treated.
2. Or, if its the wrong kind of steel, it may come out glass hard and break if you drop it on the shop floor.

On top of all that?
The blue color obtained will only be superficial, very thin, and will wear off before you get done putting it back in the gun.

Don't waste your time, and parts, trying it!

As for temps?
This might give you some idea if we are dealing with basic carbon steel.

Color & temp to draw temper.

light yellow 440
straw yellow 460
dark yellow 480
brown yellow 500
full purple 540
full blue 560 = springs
medium blue 600
light blue 640
dark red 1290
cherry red 1650
orange red 2010
white 2550
acetylene torch flame 4080


IMO: Your best bet is rust blue.

http://www.brownells.com/gunsmith-t...ng-chemicals/classic-rust-blue-prod22820.aspx

If you can boil water & use steel wool without injury, you can do it!
And it gives a very pleasing & very durable blue finish.

rc

 

[Jim K]

That process sounds a lot like what used to be called "oil blackening". It was used at Springfield Armory for years, notably on Krag and early M1903 receivers. It is done by heating the part red hot or close, then dropping it into oil. The oil burns off, leaving a deep black color that is fairly durable but that is subject to flaking which results in gray spots in the finish where the steel shows through.

Oil blackening is part of the heat treatment process, and should NEVER be used on a part that is already heat treated. Because of that, it CANNOT be redone or restored, so when Krag or Springfield receivers were found unserviceable due to a worn finish, the receiver was stripped and rust blued or, later, Parkerized.

Jim