Do thicker security films provide more tear resistance than thinner security films?

Not necessarily. The 3M understanding that thickness is no substitute for technology was the motivation behind the development and production of 3M’s ULTRA Safety & Security Window Films. Mil (.001”) for mil (.001”), 3M’s ULTRA Safety & Security Films provide greater tear resistance than standard PET films.

It was generally accepted that a film’s tear resistance increased as its thickness increased. As other film manufacturers sought to produce films in excess of 10 mils (.010”), 3M understood that such thicker films present two fundamental problems:

• Loss of film elasticity
• Increased optical distortion

Loss of Film Elasticity

A bomb blast has two phases – a positive phase, where the glass is pushed away from the source charge, and a negative phase, where the glass is pulled back toward the source charge. These two phases subject glass to significant stress. A film with little elasticity provides little cushion during such shock. Consequently, thicker films can provide less protection throughout the course of a bomb blast.

Increased Optical Distortion

Thick window films cause optical distortion from both sides of the window in a fashion similar to that of a thick pair of eyeglass lenses. This reduces an occupant’s ability to see outside with visual clarity and alters a building’s cosmetic appearance.

3M’s Response

Without sacrificing blast protection (according to third party testing) or building aesthetics, 3M developed a thinner security film comprised of an industry unique and patented system of interwoven composite polyester layers.

A multi-layered manufacturing technique creates product elasticity to allow the film to “give” with the glass during an explosion. This “give” provides the glass with a cushion during the related stress and shock.That cushion better protects occupants from flying glass shards than would a non-elastic film.

The main benefit afforded by cross-weaving polyester layers is that tear resistance is maximized. Regardless of how a window breaks, the applied film will be torn against its grain. Consequently, an 8-mil thick 3M ULTRA film is more difficult to tear than a competitor’s 8-mil thick standard film. This strong, thin-film increases occupant safety without creating the associated optical distortion of thicker films.

Only the 3M Company manufactures micro-composite multi-layered security films. However, for clients (especially government clients) who must adhere to a set specification for film thickness, 3M offers single-layered films in 7, 8, and 14 mil thicknesses.