Once you've collected your bounty of black walnuts, you're faced with the challenge of getting the thick, tough green casings off so that they can be cured and used or stored. Since there's probably a great number of them, it will most likely be to your advantage to enlist assistance. This project can be converted into an entertaining activity for teens and older children who may habitually complain of boredom. Sweeten the deal by offering a 5-cent bounty for each walnut delivered sans green casing.
Dump some of the black walnuts onto a gravel driveway or some soft earth in the yard. Drive your car over them a few times. The casings will break open, revealing the nuts.
Pull on old rubber or latex gloves and old shoes. Inner black walnut shells will stain skin and all porous surfaces after the green casings have been broken open. Wearing a bicycle helmet may be a good idea, too.
Set a black walnut on a brick, concrete block or old piece of plywood. Stomp really hard on it, smashing it with the bottom of your foot. You'll have to stomp really hard, and roll the walnut around with the sole of your foot to rub the hulls off the nuts.
Drop the hulled nuts into a brown paper bag, and the green casings into plastic garbage bags for disposal.
Use the garden hose to rinse the hulled black walnuts. You don't want to take those messy things inside yet. Put them in a large container of water to check for damaged and immature nuts. Good nuts will sink, unripe or otherwise unusable nuts will float. Discard the floaters. Your hulled black walnuts can now be cured to be used or stored.