Protective masking can wrinkle, shrink, imprint the sheet, leave adhesive residue, or become difficult to remove after heating. The allowable temperature and whether masking may remain during forming depend on the specific film and sheet product.
A film suitable for storage is not automatically suitable for thermoforming. Excessive heat, long dwell, uneven tension, aged adhesive, trapped dust, and applying heat from the masked side can all create damage.
Corrective action
The sheet supplier’s masking instructions should be followed. Film identity, age, storage, and orientation must be controlled. A trial should confirm peel behavior and surface quality after the full production cycle, including cooling and any post-form heating.
No universal masking temperature limit should be applied across acrylic, polycarbonate, PETG, ABS, and other sheets. Removing the film before forming may solve thermal damage but increases handling and contamination risk, so the process route should be chosen deliberately.