One of the greatest problems all glass decorators face is trying to keep your project pristine and unscratched. Even though there is no such animal as a piece of glass without a single scratch, we want to minimize the occurrence. When preparing a glass piece for sandcarving, I suggest using the slip sheet of your photoresist to cover the back of the glass and taping it down well; this way you have protection but still are able to see through the piece while blasting. If you are using vinyl or rubber resist, then there is no slip sheet; use some cling wrap instead, but do not forget to tape well.
—Ruth Dobbins, Professional Glass Consultant