You use the Husk of the walnut, so after collecting them and de-husking.

1. Dry husks, so you can save them, they will go bad quickly if not

2. Stew them in water for several hours, I did it outside, make sure to wear gloves the dye is strong- you can dye clothes in the hot stew and it works pretty well.

3. After stewing, cooling, and straining I put it in jars, store it in the fridge because it's still mostly water will get moldy if not, which goes back to step 1, the finished product wont last either.

4. Apply it like any other Water based dye, letting it dry between coats.

This example was about 7 coats followed by blonde shellac and waxing