Short answer: It is not required, but HIGHLY recommended.
We always highly recommend using a compatible overlaminate with a film.
Reasons for why an overlaminate should be used:
- UV protection from the sun -- this helps prevent the ink from fading as quickly
- Abrasion resistance
- Gives the thin film more body(thickness) which makes it easier to handle during installation
- Helps prevent shrinkage, especially for calendered films, by holding the film in place
- Added finishes (gloss/matte/satin)
Products that are not compatible with overlaminates:
- Cut graphic products (Series 2100/2200, 2400, 2500, 4500, 5000)
- Thick wall films (DPF 206, 207, 4200)
- Banner products (DPF 208, 210, 215, 303, 308, 310, 313, 315, 318)