The ones I get are dug from a processors ditch. I wait about 2/3 months after hunting season, and dig them out. Most will have a little stuff still on them, and if a lot, I re-bury at home. The bacteria and worms will clean them up. So will ants. After another month or so, I dig them up again and let them dry in my shop for a few more months, then they are usually ready to use. Do not dry in the sun. Most will crack. Some will crack anyway, but dry them in shade. You can clean them with bleach, but you have to be careful to not over do that. The bleach will eat the bone. When ready to make a grip, fit a wood filler shaft in the bone and anchor well with epoxy. When the epoxy is cured, you can make a slotted grip, or a hidden tang type, and have a reasonably strong grip.