One of my favorite items to use in my Craft are bones. I have a boar's skull, mole skull, turtle shells & bones, Badger skull, muskrat skull, and many others. My favorite though are the bones I acquired last year when our 30 yo horse died out in the pasture.
There was no way I was going to let all those wonderful bones from our favorite horse, go to waste! So, I waited until they were picked as clean as possible. I was hoping the buzzards would go to work on them but they didn't, only the bugs. It took about a month but they were finally "ready". One bone I could not get cleared of the skin as it had literally sealed itself on it, and one bone was taken by coyotes. But I did get all the others! They are my prize possession.
Most people would place the bones in water with a bit of bleach. I know, I've done it myself. Well, have you ever noticed how these wonderfully white bones feel chalky? Yep, that's the bleach. And it's eating your bones away, turning it to chalky dust. So absolutely do not use bleach!
Here is the way to do it and to preserve the natural beauty of the bones:
Bones to be cleaned
Large barrel(s) or buckets
Wood ash (1 cup wood ash : 1 gallon water)
Place the bones into the large barrel(s) (I needed 2).
Begin filling the barrels with water enough to cover them completely.
Pour the wood ash into the water as the barrel/bucket is being filled.
Let the bones & ash water stand for several days, check every few days to see how it's progressing.
Small bones will clean up in a few days, larger ones may take more than a week.
Once the bones are clean (note that some skin or other material may still be one them, but easily removed), remove from the ash water.
Wash, scrub, and rinse each individual bone. You may have to scrub some bones more than others depending on how much softened material is still attached.
Once completely cleaned let it dry completely.
Your bones are now clean, natural colored, will not powder and disintegrate, and are ready for what ever you want to use them for.
Here is the Old Man's skull, which sits under the buffet in the living room of our home.