Window Film Thickness

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Thickness Is No Substitute for Technology

The 3M™ understanding that thickness is no substitute for technology was the motivation behind the development and production of the latest generation of Scotchshield™ window films.

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

  1. Loss of film elasticity
  2. 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 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

In March 2002, Fortune magazine named 3M™ as America’s most innovative company. The underlying technology of 3M™ security films illustrates such innovation.

Without sacrificing blast protection or building aesthetics, 3M™ developed a thinner security film comprised of an industry unique and patented system of multi-layered, cross-woven polyester fibers. For every 2 mils of film, there are thirteen of these 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 the polyester fibers is that tear resistance is maximized. Regardless of how a window breaks, the applied film will always be torn against its grain. Consequently, a 4 mil thick 3M™ film is more difficult to tear than a competitor’s 7 mil thick product. This strong, thin film increases tenant safety without creating optical distortion.

Only the 3M™ Company manufactures 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.