wooden grips

[Heinz]

As a muzzle loading rifle builder and fairly accomplished amatuer blacksmith I may be able to shed a little light on the subject of heat bluing.


Heat coloring on iron or steel, like rust blueing has little to do with carbon being available. You can heat color very low carbon steel or iron. The various stages of iron oxides furnish the color. Heat colors will run from sraw through light blue, dark blue, purple and black.


Addition of a bone meal and charcoal cover over the parts has three major effects.

1. They increase you ability to control the temperature because they furnish an additional thermal mass.

2. Oxidation of the carbon and bone meal tends to reduce the available oxygen slowing the bluing process. If you can slow it down you can get a little thicker coat, but we are talking layers of molecules here.

3. The carbon can be slightly driven into the metal surface, or case harden. This is usually a very bad thing on steel that is of the correct hardness and makes it brittle.


The variation in carbon content can cause some variation in the depth of the color and the color itself. Case hardening usually have other "secret" ingredients like cyanide or potassium salts to enhance the color casehardening effect.


In the 18 and early 19 century "charcoal blue" was very popular and is quite striking on small pieces. But it does not hold up well. It is accomplished over a charcoal forge fire with a lot of patience. Oil queching helps to hold the color. I have never had success charcoal bluing anything bigger than a butt plate on my forge.


I have always suspected the straw color on Lugers let those who would no realize they were looking at hardened parts with a fairly hard temper. Straw is the color you use for drawing cold chisels and razors.