I use walnut dye for arrow shafts. I collected some walnuts off the ground, let them dry out in my shop then knocked the hulls off the nuts with a hammer. I pounded the hulls to a course powder with a hammer, put them in a qt jar and added hot water. This made a nice, dark stain in a few days. I didn't strain the mix, use pulp and all when wiping it on shafts. After about 3 months mould started growing in my bottle of stain so I dumped off half the liquid and replaced it with denatured alcohol. I added the alcohol 3 years ago and haven't had any mould in my stain since.