Black walnuts are expensive to purchase compared to other nuts. If you are fortunate enough to have access to a walnut tree and want to reap its harvest, you must dry--or cure--the nuts before storing them or else they will mold. Before drying black walnuts, you must hull (remove the outer husks) to reveal the shells underneath. If not, the hulls will ruin the flavor of the edible kernels inside the shells.
Set walnuts on a hard surface. Cover it with newspaper or a similar covering because the surface may become stained in the process.
Hammer one side of the walnut, then the other. Repeat until the husk comes off. Wear safety goggles for this step.
Lay the walnut shells in shallow pans. They can be layered two to three walnuts deep.
Store the walnuts in a cool, well ventilated and dry location that is out of direct sunlight (e.g., a garage). Leave them there for 2 weeks.