Carbonia Charcoal Blueing

[Duane D]

It is my understanding that the blueing on the pre WW2 Colts was called " carbonia blueing' and developed by the AMERICAN FURNACE COMPANY. I have found two services that currently offer " Carbonia Blueing.' A friend has a furnace and does very nice case harding and would like to do some old Colts. I am looking for a "cook book" type descripton of the process. I bought FIREARM BLUEING AND BROWNING by R. H. Angier but it is no help. I have been told there are instructions in volume 1 of a two volume set called Modern Gunsmithing by George V. Howe but can find no record of a book by this author. Can anyone point me in the right direction? A book? Another sight? Like any help.

[Dfariswheel]

When in doubt......Call Brownell's Gunsmith Supply. If anything is available they will know.

For old out of print gun books, there are a couple of online gun book sellers. Rutger's is one of the oldest and best.

http://www.rutgersgunbooks.com/

[cratz2]

I posted your question over in the GI section of the 1911forum

This is the response I got.

cratz2, In Howe's book Professional Gunsmithing on
page 423 and 424 there are some comments on the
bone and oil process.Parts are cleaned and mounted
in a specially built furnace where bone dust and oil or Carbonia (made by the American Gas Furnace Co, of Elizabeth, NJ) under the influence of controlled heat and absence of moisture brings about almost perfect temper bluing.According to Howe this processss was used by Smith and Wesson and Colt.
This book has been reprinted several times, it was first published in 1946. A search on out of print books will probably turn up a copy but the above is about all that is said about the process.

[James K]

I know I have that book and have seen that information but can't locate it. As I understand, though, that was part of the heat treatment process, so it really is not repeatable.

Jim

[John Lawson]

There is a picture of Colt's furnace in their 1936 catalog "A Century of Progress". Although there is no explanation, it looks like a moving link chain internally that keeps the parts in constant motion. You did not mention how large your friend's furnace cavity is. The problem with small furnaces, such as those found in an average gun shop, is that internal convections caused by rising heat will not result in an even finish.
The heat blue apparatus sold by Brownell was called "Niter Blue" in the older gunsmithing books. Read the contemporary comments on this process.
The Smith & Wesson blue was refered to as "Midnight Blue" and it is very different from the light "Carbonia" blue on early Colts. At the time, (pre-WWII) it was said to be a propriatary process.
Bear this in mind: Modern application of heat blue will match the ORIGINAL look of heat blueing on a gun. As the years pass, it gets lighter and often brighter. Therefore, do not judge a recent heat blue job by comparing it to an old gun whose finish has oxodized for years.

[BigG]

There is nothing like a fine blue job on one of these old classics to bring a lump to my throat and a quickening to my pulse.

[Jim Watson]

I went by FLG's shop today and looked in his Howe. The description there of the Carbona bluing process is very short, nothing you could use to learn the process from. Haven and Belden "A History of the Colt Revolver" reprints "A Century of Achievement"

"Frames, cylinders, barrels, slides, receivers and parts come to the bluing room direct from the polishing department. Side plates and cranes are removed. Everything is first given a bath in hot gasoline… gasoline heated to 150 deg F. This removes all dirt particles, dust, or grease that may have gathered on the way down from the polishing room. Hot air is then forced over them to eliminate all presence of moisture – the arch enemy.

After washing and drying is completed, the side plates (revolvers) are put back on. But they are put on with work screws that hide beneath the surface so that the entire surface can be completely exposed for cleaning and bluing. When finished, blued screws will replace the work screws.

All surfaces to be blued are then wiped with a solution of alcohol and whiting – a polishing compound of very fine texture. Wiped with a clean dry cloth, they are now chemically clean. From this point on until the bluing process is complete, not a human hand touches a surface to be blued.

“These are bluing racks,” interrupted Mr. Carmody. “They are built to hold a maximum number of pieces, yet allow ample room for air circulation with no chance for parts touching each other. This one is for barrels. We have racks for frames, cylinders, hammers, triggers, extractors, latches, grip safety, etc. All our screws and pins, however, are blued in bulk in those small part furnaces that you see over there.” Matched parts, such as a slide and receiver, are alternately fastened in place in the bluing rack. Racks are stored under uniform heat in closed compartments to keep them sterile and dry.

All this is preparatory to the actual bluing process itself.

Let’s take a look at the bluing room. What do we see? Twin rows of revolving drums – thirty large furnaces and eight small part furnaces.

A bluing run starts the first thing in the morning. A secret mixture of charred bone and primer is put into the furnace. Furnaces are heated up to 500 deg or more to evaporate all moisture. The racks are loaded into the bluing furnaces, the doors bolted. The furnaces slowly revolve. Pyrometers control the heat in all furnaces. Readings are taken every 15 minutes during the five hours it takes to complete the bluing process. Top heat is 650 deg.

The furnace itself is gas fired. Four burners supply the heat and it is interesting to note that the forward burner is larger to compensate for any heat loss through the doors.

The charge used in the bluing process is ground animal bone charred to chemical purity in a bone pot placed into a white hot furnace at 1400 deg hot. Two hundred pounds of bone are charred at a time, burning away all foreign matter.

The primer is bone, soaked in pure petroleum oil. Even the oil is boiled to remove moisture and foreign matter. It must be chemically pure. The primer is what gives off the smoke that keeps free oxygen away from the pieces being blued in the revolving drums. The primer and charred bone are mixed and put into the furnace before the work goes in.

What is the chemistry of bluing, anyway? How does this bluing process impart this handsome and lasting blued steel finish so famous on Colt firearms? Bluing is a combination of carbonizing and oxidizing that by heat, brings the inherent carbon of the steel through the opened pores to the surface. All the coloring is done by heat, no particle of bone ever touches the parts being blued. The smoke given off by the primer expells free oxygen from the drum leaving only sufficient to allow combustion. The primer and the charge control the composition of gas in the furnace, the heavy carbon dioxide shielding the parts from contact with oxygen. All this calls for expert knowledge and experience in mixing the proper proportions of the primer and charge not only to obtain the proper color but to create a smoke that shall be free from moisture. Otherwise, though blued, the pieces would be spotted.”

The picture shows an operator loading a furnace with a rack holding about 80 revolver frames.


That is obviously NOT a cookbook process description you can do at home in your little furnace. It purposely conceals the details of a proprietary operation so Colt and American Gas Furnace didn't give away probably unpatentable details to the competition.

I wonder how Doug Turnbull does it. He isn't saying, either.

[Duane D]

I would like to thank all of you that have responded to my call for help in exploring the possibilty of doing " Carbonia' type blueing at home. Several of you have obviously gone to some length to post information. You have also saved me a search for books that would not have been a great deal of help. I feel a renewed responsibilty to help supply others with information when I can as a result of your efforts. Again thanks and good collecting from Texas Duane Dobson

[cratz2]

A few more responses have been posted on the 1911fourm. Here's a link to the posts.

http://www.1911forum.com/forums/showthread.php?s=&threadid=34288

[Alex Johnson]

Doug Turnbull will do authentic pre-war blueing on Colts and other guns for a very reasonable price on pre-polished parts. One other blue that was probably used was charcoal blueing which gives the nice wet blue black color one sees on English guns from time to time. I beleive Howe describes this process also. In short, the parts are suspended in a bed of pure charcoal and kept away from oxygen while they are heated, periodically they are taken out and rubbed over with dry lime. The Journal of Historical Armsmaking discusses this procedure at some length. Also, you can do a temper blue quite easily, but I never felt it was all that satisfactory as a finish, Colt's do not look like a true temper blue and there finish is far more durable.

[Duane D]

Thanks Cratz2. Stumpy is correct. I had not read Angier close enough.