doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Bone charcoal for blueing?

My friend who does some very nice rust blueing recently got some charcoal to use for blueing parts.
Has anybody had experience with this and if so what is the process?

I do the process occasionally. It is very labor intensive and you can get a similar color other ways. A very good article was written in "gunmaker" the ACGG publication by Dave Norin. I believe the temp. is 800 degrees if memory serves. The freshly polished and degreased item is placed in a sealed crucible and brought up to temp., Brought out after sometime and rubbed while hot with lime and a cotton cloth, repeat until desired color is achieved. High lust polish for the best results. It is pretty and durable but not one of those jobs I personally enjoy much.

How do I go about getting a copy of that article for my friend? I understand early Colt pistols were done this way.

All of the back issues have been digitized(thank you Dennis Daigger) and a CD can purchased from the guild here:

https://www.acgg.org/index.php/contact-acgg/central-office.html

The charcoal blue process used by Colt was called the Carbona Blue Process. It is very different from the use of charcoal to produce a relatively fragile heat blue, which is more along the lines of what you get when you are tempering steel after hardening.

Carbonia blue, furnace blue? I had several parts finished by Classic guns Inc. back in the day using this process. The color of the finished parts was a very deep and shiny black, very attractive. The parts were highly polished and looked like mirrors. With all that said...I saw very little difference in these parts compared to other parts that I had blacked using good quality bluing salts. Durability of the finish also goes in favor of high quality hot blue using high quality fresh salts. The carbonia blue was also much more expensive.

Dustin

Dustin is correct. Carbonia blue was a very similar process to the Carbona Blue used by Colt.The slight difference in spelling indicates that the Carbonia process was a proprietary process used by Smith & Wesson.

When you see an old bluing job that has areas where the blue looks as if it has flaked off rather than simply wore thin, that is a good indicator that you are looking at a Carbonia or Carbona blue.

Carbona blue I have had John do for me in the past as well. The original process for Carbona involved a rotary gas furnace and oil as well as charcoal. It was a patented process develop by the American Gas Furnace co. I am not sure what John's process is. It gives a different color than true charcoal blue, more of a blue/black but very attractive. Carbona and charcoal are two different finishes but both utilize bone charcoal, only carbona uses oil.

Charcoal bluing as practiced by Victorian gun makers and still used today by the original Artisans that perfected this method who where clockmakers. If you take a close look at the screw heads and other steel parts on a vintage European clock or pocket watch they have a polish and depth of colour that is a truly striking blue indeed.
It only uses one ingredient finely powdered charcoal and an Iron pan with a very controllable but small heat source applied to the pan. Each screw or part is polished to a mirror finish then covered with charcoal powder then the temperature is very slowly increased the slower the better. Each part is removed periodically to let the oxygen in the air cause the oxide layer to increase in thickness on the surface of the item being blued also any corrections in the mirror finish is done, with the finest blue colouring arriving at about 570 degrees F.
It is an Artisan skill which I have not mastered to the point that all my clock parts do not finish with the identical blue colour but are close enough, been trying to get it right for a lot of years now and running out of practice time.

I am familiar with cold rust blue (barrels), nitre blue (pins and small fittings, and carbon blacking (trigger guards usually). I am a bit fuzzy on the distinction between carbonia blueing and carbon blacking. Same, similar, totally different ?