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The 3M understanding that thickness is no substitute
for technology was the motivation behind the development
and production of the latest generation of 3M security
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:
- Loss of film elasticity
- Increased optical distortion
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.
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.
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 14 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 6 mil
thick 3M film is more difficult to tear than a competitor's
11 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.
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