Largo, FL--Designers generally use window films on autos and buildings to block radiation-light or heat. Such films absorb part of the radiation incident on the window and reflect still more of it. Some films can attenuate RF and microwave energy.
A rapidly growing market for window films is not all that concerned with radiated energy. These applications deal with physical energy-from wind, projectiles, and intruders. Solar Gard International, Inc. supplies a line of radiation-stopping films as well as window-security films.
"Armorgard" film, a high-performance polyester film, can more than triple the strength of some glass when applied to existing windows. If the protected glass does break, the film holds the broken pieces in place and keeps the window in its frame. This characteristic of film-coated glass means less danger for building occupants-and pedestrians below a window-if a window breaks. Keeping the broken glass in the window frame also eliminates the need for time-consuming board-up until replacement glass can be ordered and installed.
Security film comes in thicknesses from 2 mil to 14 mil. For the 10-mil version, a common format, called 4-3-3, consists of three layers, 4-, 3-, and 3-mils thick. Proprietary adhesive laminates the crossed-grain layers together in a structure like that of plywood. A scratch-resistant hard coat protects the surface. All three layers may be clear, or the one closest to the glass may be a solar-control version.
"The inter-layer adhesive system doesn't set up hard," says Thomas Smith, president of Solar Gard. "On impact, the soft adhesive absorbs energy and lets the layers flex. We also use a pressure-sensitive adhesive between the film and the glass. On the 10-mil film, the adhesive is almost 1 mil thick."
Damage experienced by a two-story building in Miami illustrates two different reasons for using the security film. Located close to a heavily travelled street, the building has large windows on both levels. Traffic on the street occasionally flipped rocks, shattering first-floor windows. After Armorgard was installed, no more windows were broken by rocks.
Then, along came hurricane Andrew. Three first floor windows cracked, but stayed in place. All the second floor windows blew in. All the windows in that building now sport the security film.
Hurricanes, tornadoes, and earthquakes represent major reasons for installing the film on many buildings. Protection against burglary and vandalism provides the impetus in other cases. Solar film can replace one layer of security film to reduce the light or heat transmitted through the window.
Additional details...Contact Mark Bollegar, Solar Gard International, Inc., 10801 75th St. North, Largo, FL 34647, (813) 545-0661.