I read a lot on BYC about what to use in a dust bath. "anything" was wonderful advice! I found using ashes very intriguing. So, I decided to make my own mix! I did 1/3 garden dirt, 1/3 ashes and 1/3 wood shavings. I made a sieve from 1/4" hardware cloth to get out the bigger rocks/wood and then tossed in a little stable dry for "good measure". My 4 barred rocks argue over the dust bath since it will only comfortably fit 2 at a time. And my Colombian Rock X seem to prefer just the shavings in the coop.....maybe they don't want that icky black dirt and ash on their pretty white feathers! LOL The best part is the ash and dirt were free!