That's an interesting question parttimeartist, I guess you're talking about glass dishes and not ceramics. Dish glass is likely much thicker than your average stained glass, and it's not flat. I've never done that myself. I'm not really a professional. There are some good glass forums out there.
Stained Glassville is good at http://stainedglassville.com/glassforum/index.php
Stained Glass Town Square is good, too;
There are a few other forums on yahoo groups, too, but not as good.
The professional artists on those first two should be able to give you more expert advice than me. I hope this helped. I'm interested in hearing the answer.