You know, I really don't have a problem seeing ash on my soaps. To me, it's part of the handmaking process. When cured however, you can take a clean paper towel and wipe it off - if it offends you. It's not harmful.
I used to get ash all the time, I don't so much anymore. I'm not sure what really causes it, but haven't seen much on my soaps for a few months now.