keith,
Just a thought.Years ago soap was made with lye which was made by wetting wood ashes.Lye is pretty corrosive,do you think it might make metal in contact with wood de-oiled with wet wood ash rust? Remember the salt dried Browning stocks? It seems that DE should be as gentle as whiting or kitty litter, and if you have any left over, you can kill insects in the garden with it.
Mike