Text 02Security Window Film for Wisconsin Glass

Security window film is a thick, clear layer bonded to the inside face of your glass. Kepler's is K-Shield, an 8 mil film the company describes as designed to help hold shattered glass together while adding UV protection. It does not stop the glass breaking. It stops the broken glass going anywhere: the pieces stay stuck to the film and the film stays stuck to the pane, so the open hole you would normally be left with is not there. That is what makes it useful against forced entry, storm debris and accidents alike. In Wisconsin it goes on schools, shop fronts, offices, public buildings and houses.

For heat and glare films, see the commercial window tinting page.

Glass fails in one hit because nothing is holding it together. K-Shield gives it that: a continuous 8 mil sheet bonded across the inside face, so the energy of a blow spreads through the film instead of ending at a hole. The pane cracks and stays where it is. Whoever is outside now has to work at it, repeatedly, in the open and making noise, which is exactly what a smash-and-grab is designed to avoid. The same mechanism helps in an accident: someone stumbling into a lobby window leaves a cracked pane rather than a floor of shards. Kepler does not market K-Shield as bullet, blast or storm rated, and it should not be bought as though it were. It buys time and it holds glass, and both are worth having.

For damage to the outside face of the glass, see anti-graffiti film.

Clean it the way you would clean the glass, minus anything harsh: a soft microfiber cloth, clean water and a mild cleaner with no ammonia in it. Skip scrapers, scouring pads and abrasive creams, because the film marks more easily than glass does. Your dealer will tell you how long to leave it before the first clean.

Looked after, it stays clear and keeps doing its job, and Kepler's 10-year limited warranty covers the film itself against defects.

Tempered glass is made to break into small blunt beads rather than shards, which is safer, but it means the whole pane lets go at once. Film holds those beads together, and the sheet it forms can still be pushed out of the frame at the edges. That is why edge attachment matters most on tempered glass: anchoring the film to the frame rather than only to the pane. Ask your dealer to look at the frame and specify what your glass needs.

Graffiti and etching on the outer face need anti-graffiti film.

Laminated glass already has a plastic interlayer between two panes, so it is built to hold together when it breaks - the fragments stick to the interlayer. K-Shield adds a second layer of retention on the inside face, and adds UV protection while it is there. Whether it is worth doing depends on the opening and what you are protecting against, so let your dealer look at it.

Thickness is the number everyone asks about, and it is not the whole answer. How a filmed window behaves depends on the film, the glass underneath it and how the edges are handled at the frame. Kepler's K-Shield is 8 mil, a heavy gauge for retention work, and it carries Kepler's 10-year limited film warranty; thermal glass breakage cover for five years is available where the installing dealer qualifies for it, so ask what applies to your job. Past that, ask your dealer to look at your actual glass - annealed, tempered and laminated all break differently and all want a different approach.

Partly, and it depends which side of the glass the damage is on. K-Shield is bonded to the inside face, so it deals with impact - something thrown at the window, or someone working at it to get in. Spray paint, etching and scratching all happen outside and no inside film can help with those. Anti-graffiti film is made for that job: a thin layer fitted to the outer face with a removable adhesive, so the film takes the damage and gets replaced rather than the glass. Security film is thicker, bonded inside and deliberately hard to peel off. If your trouble is on the outsideof the glass, look at anti-graffiti film instead. It is a different product for a different kind of outside damage.

They are the same product described two ways. Safety is about people: keeping broken glass off the floor after an accident or a storm. Security is about intent: making a window slow and loud to get through. K-Shield does both, because both come from the same thing - a thick film bonded across the pane, holding the fragments in place.

What it is not is a solar film. For heat, glare or privacy control you want the commercial window tinting page.

Neither one helps with graffiti or etching; that is anti-graffiti film.

Annealed glass is ordinary untreated glass, and it is what a lot of older Wisconsin buildings still have. It breaks into large pieces with sharp edges and dagger points, which are the ones that do the damage. That is the glass security film helps most: K-Shield bonds across the face and the broken pieces stay stuck to it instead of falling inward. Worth saying plainly, though: annealed glass of any thickness does not meet safety glazing requirements on its own, film or no film. Where code applies to an opening, that is a conversation with your building official.

For heat, glare and privacy films, see the commercial window tinting page.

Sometimes, and it depends on the glass and the frame. Film applied to the pane alone holds the glass together, but the whole filmed pane can still be pushed out of its frame - that is the known weak point in a film-only job, and it is why manufacturers make attachment systems that anchor the film to the frame itself. It matters most on tempered glass, which releases the entire pane at once. On annealed and laminated glass it is needed less often. This is not a decision to make from a web page: your Kepler dealer should look at the actual openings and tell you.