| Most overhead glazing to be found in our many | | | | adhesive. The film is available in varying |
| shopping centres and public buildings is heat | | | | thicknesses from 100 micron up to 350 micron |
| tempered toughened glass. This type of glass is | | | | depending on the specific requirement. For |
| the material of choice as opposed to laminated | | | | example for facilitating safe breakage of annealed |
| glass because of its lighter weight however the | | | | glass in a door or side panel, 100 micron will |
| downside to this type of glass is fragmentation in | | | | achieve the necessary En safety standards as |
| the event of breakage. | | | | specified in Regulation 14. For "anti bandit" or blast |
| Breakage can occur for a number of reasons | | | | mitigation a much thicker film is usually required. |
| including vandalism and accidental impact however | | | | For the purpose of glass fragment containment a |
| the main cause can be viewed as something of a | | | | 175 or 200 micron film is normally more than |
| phenomenon. Spontaneous breakage of | | | | adequate.This combined with an edge retention |
| toughened glass is the collective name given to | | | | system is by far the most effective solution. |
| sudden shattering for no apparent reason. In | | | | There are three main types of edge retention |
| actual fact there are several possible contributory | | | | methods used in the window film industry.They |
| factors that can lead to such an event, these | | | | are: |
| being edge damage during installation, tight fitting | | | | 1. Aluminium profile - An angled aluminium bead |
| of glass in the frame, wind load and something | | | | held in place with a high specification double sided |
| called nickel sulphide inclusion. | | | | tape. One side bonded to the newly filmed glass |
| Nickel sulphide inclusion is the occurrence of | | | | and the other to the window frame. |
| impurities left within glass during the manufacturing | | | | 2. Two parallel plastic beads held together down |
| process. These can be in the form of tiny | | | | the centre by a flexible plastic fillet. This again |
| stainless steel shavings left behind by the | | | | enables one edge to be bonded to the glass using |
| machinery used in the manufacturing and handling | | | | the same double sided tape and the other to the |
| processes or minute pieces of brick from the | | | | frame. |
| inside of the heat furnace.The presence of these | | | | 3. Structural Silicone - A large fillet of a highly |
| inclusions will often in time cause an anomaly with | | | | aggressive structural silicone such as Dow Corning |
| the surrounding glass during times of heat or | | | | 995 is applied to the frame and the filmed glass. |
| kinetic stress resulting in an "explosive" outcome. | | | | From an aesthetic point of view the aluminium |
| How do you negate the potential danger of | | | | profile is probably the best method as this can be |
| shattered glass falling on to unsuspecting people | | | | powder coated to match the existing frame |
| below? The simple answer to this is to install a | | | | colour however not all frame profiles allow for this |
| containment solution consisting of a tough | | | | method to be adopted. |
| polyester window film in conjunction with an edge | | | | Providing that safe access to the glazing can be |
| retention system. Safety or security window film | | | | achieved, the application of window film with edge |
| is an optically clear, smoked or reflective laminate | | | | retention is the only realistic way of countering a |
| adhered to glazing by an extremely strong | | | | very real problem. |