What is the best way to clean aromatherapy bowls?

Question

The black just won't come off and it's eating the other oils in five minutes, any suggestions?

Answer 1

What are they made of? I'd say, look up Heloise's household tips for cleaning various substances, or one of those household hint sites. The Queen of Clean? Is that her name?

But stay away from chemicals--they'll kinda counteract the whole "therapy" part.