If you are using a laser to cut your masks, you have to be careful about the contents of polyvinyl chloride in any masking material, which can fog up your laser’s mirrors and is not a good thing, not to mention it is not healthy to breathe such fumes.
But even if you do not use a laser, the reason not to use sign vinyl is a big one: those materials are made with strong adhesives which are meant to keep the material glued to a substrate and not release easily. When trying to remove such vinyls after blasting, they often leave much of their adhesive on the glass, which then must be removed with a solvent of some kind. It is not only not desirable to be exposed to solvents, but also costs extra time and labor, affecting your bottom line.
—Ruth Dobbins, Professional Glass Consultants