Does photoresist film for sandcarving need to be dried after washout?

Since the material is wet after the washout, it has to be dried (unless you are using dry-processed film). You could do this by hanging the sheet up to dry, but for production, it is best to use a dryer, which keeps a constant temperature and allows you to dry at least four full sheets at a time within a predictable time period. The sheets need to reach a drying point where there are no more moist/milky spots in the material. At that state, the sheet can adhere to a sheet of silicon release paper for future use.

—Professional Glass Consultant