Staining the checkering is secondary to the process. Just as metal can be case hardened, almost any species of wood can be case hardened. I will explain...have you ever tried to drive a nail through a piece of OLD yellow pine? It's near impossible without bending the nail. Turpentine is a derivitive of yellow pine. when you are finished checkering the walnut stock, in a small ashtray or bottle cap mix 1/2 teaspoon terpentine with 4 or 5 drops of black oil based paint like rustoleum. then apply with a toothbrush in both directions of the grooves. allow it to soak in for several minutes while you remove the excess terps from the tooth brush with a paper towel, then brush again in both directions to remove excess terps from the checkering. after about one hour the terpentine is dry on both the checkering and the old tooth brush and the tooth brush is 5 times stiffer than when you started. Brush again with the stiffened (dry) tooth brush to polish the checkering. This concept can be fiddled with with reasonable success. On fine checkering or high grade wood where no staining is wanted, three or four drinks of turpentine without color added will case harden the checkering, then if you like, one last drink of terps with coloring (or 3 drops of finish) can be applied. Allow 24 hrs between terp applications for maximum hardening of the checkering. I was taught this technique 25+ yrs ago by a Belgian/American surveyor from North Carolina, who grew up in Liege. His whole family participated in the gunsmithing cottage industry for several generations. Below is the first gun I ever case hardened the checkering using this technique. I checked and hardened it back in 1981 and the gun has been in service as a shooter ever since. The diamonds have withstood the test of time and use. Please remember where you first learned this concept.
