Safety films differ from normal heat protection films in two important aspects. Safety films have a thicker and stronger adhesive layer. Their function is to hold the glass panel together in case of breakage, therefore preventing shards of glass from flying around, and also to slow down intrusion through the window. Safety films are available in transparent, combined heat protective, privacy protective and exterior versions. The anti-breakage properties of such materials is defined by standard tests – in Europe, breakage tests according to EN12600 and EN356 are used. During the EN12600 test, a pendulum hits the filmed glass surface, which is followed by the examination of the breakage pattern and the quantity of shards that left the glass panel. The certification of the film is usually 2B2 or 1B1, the latter being the higher one. During the EN356 test, a steel ball is dropped on the filmes glass surface, and it is checked if the glass breaks through or not. Window films usually reach the P1A or P2A certification – P2A is the higher category, known previously as A1 according to the DIN standard.
Transparent safety films in SkyFol’s range: SkyFol S2, SkyFol S4, SkyFol S7, SkyFol S11, SkyFol S12
Combined heat protective & safety films in SkyFol’s range: SkyFol SSI420, SkyFol SSI440, SkyFol SDR435, SkyFol SDR460
Privacy protective safety films in SkyFol’s range: SkyFol M5
Exterior safety films in SkyFol’s range: SkyFol XT4M, SkyFol XT7M
It is important to point out in the beginning that often conventional window films also stick to polycarbonate surfaces, it is not a coincidence that films exist which are specifically manufactured for polycarbonate, with the biggest difference in their adhesive. Films for polycarbonate have an air permeable and removable adhesive. Air permeability is highly important to avoid bubbling – the adhesive layer of conventional window films do not let through gases leaving the PC material, so they get detached from the surface with the formation of bubbles. Removeability is another very important factor, since the adhesive of normal window films might enter a reaction with the polycarbonate surface, therefore becoming practically impossible to remove. It is crucial to use the appropriate material on each different surface.
SkyFol’s range includes three films for polycarbonate: SkyFol XT16SPC (exterior silver reflective film for heat protection), SkyFol XT4MPC (transparent exterior film for surface protection), SkyFol S4PC (transparent interior film for surface protection).
Spectrally selective window films filter specific wavelength ranges in a different way. The solar spectrum reaching the glass surface can be divided into three parts: UV, visible light and infrared radiation. Spectrally selective films filter IR strongly, while they have high visible light transmission values. The best indicator of the lightness and heat protection feature of these films is luminous efficacy, that is visible light transmission divided by the shading coefficient. We can generally speak of spectrally selective films in case of a value greater than 1. Spectrally selective films are manufactured with a special metallization, usually with silver, gold and other precious metals. A lot of manufacturers try to sell their heat absorbing films as spectrally selective, which is rather misleading – it is best to avoid these materials and to select a truly spectrally selective film.
SkyFol offers the following spectrally selective films in its range: SkyFol P70, SkyFol XT67CV, SkyFol XT76CV.
Dual reflective films fall into two categories: one of them contain a dual metallic layer with different reflectivities (the outer layer is aluminum metallized, while the inner is generally nickel-chrome), and the other one has a coloured layer on the inside, so reflectivity is reduced. These films were developed to provide strong heat protection, while at the same time with a lower interior reflectivity to provide a better look from the inside. Such materials are primarily used as substitutes for silver reflective films in apartments and offices, as well as in places where a lot of light falls on the films surface from the inside with a disturbing reflective effect, e.g. in restaurants. The dual metallized technology is more efficient than metallized-dyed, but the decrease of reflectivity is not so cinsiderable. Generally speaking, this is a good choice with darker films, but from the visible light transmission on 35%, the difference as compared to a neutral film is very small – energetically, a reflective silver film is a much more efficient option.
SkyFol’s range includes metallized-dyed films in the DR (Dual Reflective) series.
Silver reflective metallized window films, as well as their alternatives with a coloured lamination are generally called reflective films. These products contain aluminum, which is incorporated onto the polyester surface via a vapour deposition process. This is a cheap and efficient procedure, hence these generally are the least expensive window films. The technical parameters of the film are determined by the thickness of the metallic layer, as in their basic form, no other layer is present. The most widely used versions has a visible light transmission of 15%, 20%, 35% and 50%, but technically production is possible with VLT values in the range of 0-80%. There are films laminated with a coloured layer as well, where the coloured layer is laminated onto the silver reflective film – the coloured side will look towards the outside; dual reflective films are manufactured using a similar process, but in this case the coloured side in inside – more on this issue in part 4). Coloured films are recommended only if absolutely justified, because the heat absorption of such films is generally higher, and also because the coloured film will inevitably get fainter as time passes.
Reflective films in SkyFol’s range are called SI (Silverall). In their coloured version, bronze, blue, green and gold films are available.