[Parker Bachelder (Brad's Profile)]

It is imposible to quickly explain all of the variables that effect color case hardening. Contrary to conjecture and rumor the process is controlable and predictable.

two constants in the process are: type of metal, machineing reliefs.
The type of metal cast, forged, or rolled dteel, absorb carbon at different rates. Rolled steel, due to molecular density absorbs more carbon than cast steel. Sideplates and triggerplates are usually rolled steel accounting for deeper, longer lasting colors. Recievers cast or forged, absorb less carbon or color affecting durability.
Machineing translates to repeatable patterns in like parts. In the heat up phase thick areas remain cooler than thin areas. at quench thick areas cool slower that thin areas. Two prime examples of this in Parkers are the center band of color on triggerplates at the point of machineing for the cocking slide. The centers of the water table flats at the hammer spring pockets.
Parker forearm irons form a distinctive pattern at the "T", we refer to this pattern as "antlers". This is created by drawback or outside cooling at quench.
Pin holes, screw holes and edges drawback or turn straw or grey due to rapid cooling.
Color ranges, contrast, machineing patterns and patina, are all controlled with process variations in packing materials, tempature,surface preperation and exposure to oxygen. A careful educated study of original specimens is the most important factor in creating a process formula. Every manufacturer used the same basic process. The secret ingredents were not magical or chemical. The variations were in process crontrols and specific steel types.
We utilize over 20 different process formulas to yiels specific colors and patterns by brand and era.

Brad