Blast Test Video: Fragment Retention Performance
Kirtland Air Force Base, New Mexico
Blast Resistance Videos
Window with No Film Attachment
Window with 2-Sided Film Attachment
Window with 4-Sided Film Attachment
Window with Wet Film Attachment
Hurricane Resistance Videos: Tests conducted in compliance with Miami-Dade protocols
Small Missile Impact Test
Large Missile 4 lb. Impact Test
Download Test Report
Launch Project Gallery for Fragment Retention Window Films
Proven Protection: Bomb Blasts and Hurricane Force Winds
Flying glass is the primary source of injuries and a major source of damage in an explosion or hurricane force winds. Hurricane/windstorm fragment retention film prevents the glass from shattering inward during extreme winds and also acts as a barrier to heavy hurricane rain and flying debris. Bomb blast fragment retention film also prevents glass from becoming airborne in the event of a terrorist attack or other blast-related situation.
Fragment Retention Window Film
Fragment retention window films are designed to increase the shatter resistance of glass and are similar to regular window films in that they are polyester laminates. The difference, however, is that these products are usually thicker – offered in thicknesses ranging from 4 to 14mils – and use a heavier and more aggressive adhesive system. This material is available in clear or a variety of tinted Solar Energy rejecting versions to get not only the benefit of increased glass strength but to conserve energy and make the building more comfortable.
How Fragment Retention Film Is Made
Fragment Retention Window Films are the result of a very sophisticated manufacturing process using only the finest raw materials and state of the art technology.
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Window Attachment Options
Depending on fragment retention performance and budget constraints, fragment retention window film can be installed on the glass only (known as a daylight application) or physically attached to the window frame (known as attached systems).
Daylight Application
The easiest, quickest and least expensive method is to use the daylight application. The daylight application involves placing the fragment retention window films onto the vision area of the glass only. This approach will hold glass fragments together but does little to increase the blast resistance of the glazing system. If the blast pressures exceed the strength of the glass itself - somewhere between ½ and 1 psi - the entire filmed piece of glass could be pushed into or sucked out of the room. The purpose of the fragment retention window film is to hold the glass shards together in one piece. Since the glass fails before the film, minimum thickness fragment retention films are usually specified.
Attached Systems
To address the requirements of some of our more vulnerable customers with advanced security needs, Commercial Window Shield developed its proprietary Blastight window film attachment systems. The attachment can be on 1, 2 or all 4 sides of the frame and can be achieved with either a mechanical (metal) or chemical (structural silicone) attachment.
Mechanical Systems
Mechanical systems are done using some type of metal batten system similar to our Blastight™ Film Attachment System. The Blastight™ is secured with screws or other fasteners. Mechanical systems can be configured for various strengths in that they can be attached on one side, two sides or on all four sides.
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Top attachment (one-sided) is the method specified and used by the FBI. To keep the glass from being ejected out of the window frame and into the room, the film is overlapped onto the head of the window frame and mechanically attached with screws using a batten system. When the other three unattached sides of the glass fail, the film holds the glass together in one piece and the glass/film unit hinges up toward the ceiling and then falls back into place - similar to a "doggy door". This system is designed to allow the glass to fail, which relieves blast pressures. Because of this, the film itself does not "see" high pressures and a minimum thickness fragment retention film is generally specified. This system should only be used with single pane glass.
Two-sided attachments increase blast resistance to an existing window or glazing system. The film is overlapped onto two sides of the window frame - either top and bottom - or usually side to side. The two unattached sides will fail and the blast pressure will be vented. The attached sides are designed to hold the glass at the window opening. This system is very strong and failure of this system is usually a result of the window frame itself giving way. Since the film receives a much higher load than either daylight or one-sided attachments, heavier gauge films are required.
Four-sided attachments are the strongest mechanical attachment system. The films are designed to withstand tremendous loads and the full pressure of a blast event is transferred to the window framing. Most standard commercial windows or storefront systems cannot withstand this intense pressure and the window frame system will fail before the film/attachment does. Four-sided attachments are often specified in Day Care facilities, areas where no glass particles can afford to penetrate, or as an inexpensive insurance policy against a large blast event. Since the film will experience severe pressure loads, heavier gauge films are required.
Wet Glaze Systems
Wet glaze systems are similar to mechanical attachments except a silicone adhesive (caulking) is used for the attachment instead of a metal batten. This method is also sometimes called a chemical attachment. The film is applied to the vision area of the glass or daylight opening and then a bead of high strength; high quality structural adhesive is placed around the perimeter of the window frame. It is imperative that a minimum ½" of adhesive contact the film and ½" of adhesive contact the window frame. This system is comparable to a four-side mechanical. It is easier to get a "quality" installation but it is highly "installer" sensitive. This system may be the only choice for certain window frame types. It also may be ideally suited to historical buildings - especially with windows with multiple small panes where a mechanical attachment can't be used or won't fit. It is imperative that the proper thickness and overlap of structural silicone be used. Heavier gauge films are generally used with this system. Link to view a paper written by Dow Corning on the proper use of structural silicone.
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The above systems have been tested, both in a shock tube at Wilfred Baker Engineering and in open air tests conducted by Applied Research Associates. The systems meet or exceed the standards required by the United States General Services Administration (GSA) for blast mitigation.
NOTE: Please contact us and we will look at any project and give you an opinion of the appropriate type of installation to use.
A Major Threat: Flying Glass
Glass is usually the weakest security link in a building, and flying glass is the primary source of injuries in an explosion or other fragmentation event.
The images below detail the damage effect radius of glass and other flying debris on surrounding buildings sustained during the Oklahoma City bombing.
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"I'm always happy to provide a reference for your company. You guys did a terrific job under extraordinary circumstances. I tell people that, and
unfortunately there is no good way to put it in the proper perspective for
them, because they weren't here. Please feel free to list me as a reference anytime."
– Don White, Superintendent
U.S. Capitol Building
(Where, immediately after 9/11, Commercial Window Shield was contracted to install security film on the Capitol Building's 9,000 windows, completing the complex installation within 30 working days.)