I gently swab out the ash with a pipe cleaner after each bowl. In my experience, using ash, honey, etc. to build cake leads to weak crumbly cake. And there's nothing you can do (short of giving up smoking) to stop cake from building. As I've said elsewhere, I look at cake the way I look at shaving. At first, it was really exciting and I couldn't wait for more whiskers to show up. But eventually, realized I was going to be scraping this shit off of my face for the rest of my life, and all romanticism disappeared. Same with cake; when you're first starting, it's a big concern. Eventually, it'll just be another chore (though still more enjoyable than shaving, if you ask me!)