You need to chop up the hulls from the walnuts. The husks are antiparasitic, antifungal and antibacterial. They are designed to keep worms out of the walnuts. The second you cut into them they are yellow, but they instantly start turning brown and they will stain your fingers, so don't be like me -- wear gloves! My fingers were stained brown for days and nothing would remove it!
The tincture can supposedly be used like iodine to clean wounds. The walnut hulls smelled just like iodine when I was chopping them up. Black walnut tincture can also be used to deworm for various parasites. Some people use it to deworm their animals. Among other things, it may help lower cholesterol and blood pressure, and may treat heartburn and colic. It is known to be good for fighting candida or yeast in the system. Some even say it fights cancer, syphilis, and malaria.
Black walnut tincture is strong and you should consult your doctor before using. It is not recommended that you take it for longer than two weeks, and it is not recommended for use in pregnant women.
I think it will be handy to have around. I will let this cure for a month in a dark place before straining out the hulls and bottling it.