Once the husk is off, wash the unshelled nuts in a bucket to remove excess juice and debris. Unfilled nuts will float and should be removed. After washing, the unshelled nuts need to be dried and cured, if they aren't going to be cracked right away. To dry, spread out freshly husked and washed nuts in thin layers in a well-ventilated area out of direct sunlight for several weeks. Once dry, unshelled nuts can be stored in a cool, dry place in mesh bags, burlap sacks or baskets for up to a year.
Black walnuts have a hard shell.
Hand-held nutcrackers seldom work. A hammer, a block of wood, a vise or big rocks are better choices. Special pressure-type crackers efficiently crack individual nuts end to end. Nut shells can be pre-conditioned before cracking. If shells still seem brittle, soak them in hot tap water just before cracking.