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Security films have traditionally been installed using
a technique known as a daylight application. The shatter film
is applied to the window and bonded to the glass when
the pressure sensitive adhesive is activated by a mild
solution of dishwashing detergent and water. Excess
fragment retention film is then trimmed to fit against the window's gaskets
to create a finished product.
After the tragedy of Oklahoma City in 1995, consideration
was given to the fact that the entire glass pane could
be blown out of the frame given a severe explosion.
Security film manufacturers responded to this additional threat
by developing attachment systems. There are two main types - a mechanical batten system, and a wet glaze
attachment system.
During a mechanical batten system installation, the
blast-resistant film is applied to the glass in a fashion similar to
that of a daylight application. But rather than being
trimmed to fit flush against the gaskets, the security film overlaps
the window frame on one, two, or four sides and is then
clamped to the frame at a 90° angle using a system
of metal bars and screws. This 90° angle inherently
weakens the security film by subjecting it to shear stress and the system of metal bars and screws
alter the window's appearance. Additionally, this type
of installation is time-consuming and very expensive.
A less expensive and more effective installation technique
is a wet glaze attachment system. Wet glaze attachment systems
use a high strength structural silicone adhesive to anchor the
security film, glass, and window frame to each other. The anti-shatter film
is applied to the glass in a fashion similar to that
of a daylight application except that the gaskets are
trimmed and the film's edges are inserted behind the
window frame. A bead of silicone is then applied flush
against the frame to overlap the security film and take the place
of the original gaskets. 3M developed its own wet glaze
system, the Ultraflex
Window System, which uses a Dow Corning 995®
structural silicone adhesive. This method is less costly
than a mechanical batten system and is approved for
Washington, DC historical buildings.
During a test conducted for 3M by Applied Research
Associates, a GSA-approved independent testing agency, results showed
that 3M security films achieved higher levels of protection when
anchored to the window frame by Ultraflex
than by a mechanical batten bar system.
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