Adventures in Color Case Hardening

Case hardened receiver and hammer

Color case hardening is a process that adds carbon to steel thereby hardening the surface of the steel. Colors such as blue, orange, and yellow are produced by this process. This can give a very appealing appearance to parts of a firearm that are case hardened, as well as hardening the parts.

In this article we will show the preparation and case hardening of an old Remington Falling Block 22 rifle. The most time-consuming part of the job is preparation of the parts to be case hardened.

Receiver with stock and barrel removed
Receiver and parts after soaking in Evapo- Rust.
Receiver with all parts removed

Preparation

Since this old gun had quite a bit of rust and accumulation of crud, it was disassembled and soaked in Evapo-Rust. After soaking and some scrubbing, polishing was done. Polishing was done with 220, 320, 400 grit sandpaper. When polishing the parts, care must be taken to keep all the edges sharp and all lettering intact. Polishing is time consuming, but there is no substitute for careful polishing.

Hammer Before polishing
Polishing receiver

Hammer after polishing

When all parts have been polished, they must be de-greased. A rag and acetone does a good job. Care must be taken to remove all fingerprints and to keep from putting more fingerprints on the parts until the process is completed.

Loading The Crucible

Charcoal and Receiver in Crucible

The crucible is filled with charcoal and the parts to be case hardened. Wood charcoal and bone charcoal are mixed together in a separate container and then the crucible is partly filled with the mixture. (We used the ratio of bone and wood charcoal that is given by Brownell’s for this project.) After the charcoal is in the bottom of the crucible, the parts can be placed on top of the bottom layer of charcoal and packed tightly with more charcoal. The goal is to have the parts totally surrounded with charcoal, with no voids, and with no parts touching one another. When the crucible is packed completely full of charcoal with no voids, the lid is put on and it is ready to go into the kiln. The Kiln is heated to 1400 degrees and when the temperature has stabilized the crucible is put into the kiln for about 1 1/2 hours.

Quenching The Parts

The parts need to be quenched as soon as possible after removing them from the kiln. This is accomplished be dumping them into a container of aerated water. The crucible is taken out of the kiln, the lid removed, and the parts and charcoal are quickly dumped into the water. This should be done quickly so that exposure to air is minimized. Appropriate protective clothing, gloves, and eye protection needs to be worn, as steam, water, and charcoal will come out of the water as the hot parts hit. This is spectacular to watch but not something you want to get on bare skin.

Finishing The Job

Once the parts are cool enough to handle, remove them from the water and blow them dry. Putting them in a 400-degree oven for one hour will help remove any stresses from the process. A coating of lacquer or clear DuraCoat can be applied to protect the color from wear.

Color case hardening is an interesting project. There is lots of history and as many ideas of how to do it as there are people doing it. There are lots of variables that could be tried as well as many opinions as to how it should be done. Our project turned out pretty well and we are anxious to get another case hardening project underway. If you have a color case hardening project in mind and don’t have the equipment to do your own, contact Craig at Craig’s Outdoor Sports. www.craigsoutdoorsports.com The following videos show our project underway.