doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Coloring of parts (Nitre Bluing)

Note that even though full annealing will not take place raising the temp of a hardened part will draw or temper the hardness. Raising a case hardened part to 750-800�F will definitely temper out the "File Hardness" it obtained on quench.
Personally I would not see this as a problem on the top lever, but is a definite reason for not "Torch Coloring" frames. Likewise I would personally not want a double frame which was originally case hardened, even if I were willing to switch to a blue color ,done by any method which exceeded 300�F.

Shawn, thanks for the information. I don't think I will go that high, 825.

If worse comes to worse I will cold blue it a bunch of times, or I will harden a piece of drill rod and draw it back to about 600 deg, which should be blue, and try that first.
The only thing bad about that is they are not the same compositon. I believe L.C. Smith used mostly 6120 on a lot of their case hardened parts, and the drill rod definitely has more carbon content.

Miller, That's want I thought. And yes, does it make a difference? I don't believe so. I'm wondering if Hunter Arms did polish the top of the lever and when case hardened, it turned that blue when annealed.

Nitre bluing at 825F just to say its charcoal bluing seems like a waste of money in my opinion. You might as well be actually charcoal bluing the parts at that temperature and if they were going to say one thing and do another why not just save yourself some time and money and black oxide the parts at 295F and call it charcoal bluing. Im not calling anyone a liar or sticking up for anyone, Im just interested by the story.

Channing Will

I can put this to rest. I used to work for Doug and can say that all of his finishes are as advertised - including charcoal blue.

Best, Dan

Dan,
Could you tell us more about Turnbull's charcoal blue process? I was told that by the late Bill Adair. He said that a former Turnbull employee told him that but had no way of verifying it. I guess that now We know it is not true. Thanks

Shawn,

I worked as a stockmaker for Doug so I was never taught any specifics as to the metal finishing processes (nor would I divulge any trade secrets of Doug's)! But I can tell you with total confidence that charcoal bluing was (and I'm sure still is) done in the traditional process using charcoal and oven. Nitre bluing was of course also offered but was reserved for smaller parts and the blue was generally the lower heat bright blues most associate with nitre.

Best, Dan

Thanks Dan.
I've discussed the subject many times, at length with Doug and have had many parts finished by most all of his methods and was about to call bullsh!t on that third hand BS.

Hagn action color case hardened by Turnbull Restoration with a request for muted colors. And it's hard too. Turn-around; MT to NY to MT, less that 30 days.

Thermometer came today. Built a holder for it and a place to hang parts from.
I had two bottles of stump remover (potassium nitrate) and went and bought another. Pourng the two bottles of crystals into the loaf pan brought the level to about 1 1/2" from the top. Added a little more and set on the burner. Partially disolved at 600 deg and fluid was dark, a few minutes later it was better, more translucent, but the tmeperature would not go above 600 deg. Started with triggers, left in about 6 minutes, took out and quenched in oil, left a heavy film of junk on them. Did a few screws, and quencehd them in oil also.Did the top lever, left in longer but this time I flushed it with water, took the scum off under the water. Did the trigger guard, left in about 10 minutes,, but the wires weren't long enough so I fastended the "S" hooks on the side, but the tirgger guard was on it's die also. When finished it came out blotchy.
I am fairly happy with the screws, the tip lever, trigger guard will have to be done over when I find a burner that will go higher. It states on the side of the burner case that the output is 34k/btu hr. I was only using one burner of the two. What should I look for as to output of burner/s?

Had a fan behind me blowing out the door. Used safety glasses and a face shield aldong with welders gloves.


I have to go get another bottle of stump remover to bring the level up. That would be 4 total in a pan that measures 10" inside x 4" wide x 3" high (approx)

Also do you have to polish the parts after? Mine had a matte finish on them, I buffed them with a rag and they looked much better.

David, several years ago I did nitre blueing mainly on double trigger guards. I used a cast iron dutch oven with good results, is it possible the container you are using is too light and won't retain the heat? My heat source was an old cast iron 2 burner gas set up

James, that is possible, but Brownell's sells a welded pan that doesn't look that thick. It's probably 1/16" or so.
I think I need a bigger burner. The temperature held at 600 the whole time I was coloring.