There are several different types of window film, though all have one basic ingredient in common: polyester film. The depth of the polyester film varies from 2 to 7 millimeters, while some types of film consist of a number of thin layers stacked on top of one another. On the inner surface, the film is fitted with a water-activated or pressure sensitive coating, and a hard, scratch-resistant finish is applied on the exposed outer surface.
Special chemical UV blockers (cyclic imino esters) are added to the film to prevent ultraviolent radiation and this basic composition makes up a typical window film for general shatter resistance and UV protection.
Once the film is created, three different technologies are used to bring out unique features and characteristics in the final product:
Dyed film adds a layer of heat-absorbing dye to the mix. You might think that because the film absorbs heat, it will make the inside of the car heat up as well. But in reality, the heat that escapes the film transfers to the glass, and dissipates quickly outward along with the outside airflow. On still days, a small amount of heat does bleed through, although the average daily speed of natural air movement is around 15mph, which means there’s always enough wind to keep the heat moving.
The next two kinds of film include a reflective coating of metallic particles achieved either by vacuum coating/metallizing (deposition technology) or advanced metallizing (sputtering technology). With both of these film types, another layer of film is added to give protection to the reflective coating, and the metallic particles resist heat by reflecting it away before it reaches the glass.ble-glazed windows restrict air movement between panes, so if you have thermal glass windows you’ll have to give this film a miss and consider one of the other film types.
Deposition technology: during the deposition process, a tank holding metal ingots (mostly nickel-chrome or aluminum, and sometimes copper) is fed with film and pressurized to create a vacuum. Argon gas is then pumped into the tank, heating the ingots and causing the metallic particles to rise and cover the film’s surface. The final concentration of metal in the deposition process is determined by how long it takes for the film to move through the tank’s chamber.
The deposited film method produces good results with relatively low cost involved, although it is only viable for select applications. Because the metal particles are much larger in comparison to that of the underlying film, the coating needs to be spread thickly across the surface. This results in a darker, more reflective tint.
Caveat: there aren’t many metals suitable for deposition, meaning choice between products is quite limited.
Compared to the limited choice in materials of deposited film, over 25 distinct metals are suitable for use in sputtering, and the resulting film is also much lighter. The metal layer is extremely fine (down to one-hundredths the thickness of human hair), and depending on what metals are used, it’s highly effective at blocking certain radiation bands from direct sunlight. Sputtered film produces minimal mirror effect, color shifting, and heat absorption while retaining high reflectivity of radiation. The cost to manufacture films using sputtering is unsurprisingly high, which means these films can be quite a bit pricier than most. Basic components found in sputtered film are: layers of polyester with adhesive, metallized, and scratch-resistant coatings.Sputtering technology is a highly complex process, and like deposition technology, the magic takes place in a special vacuum chamber. There’s a big difference here, though, as the metallizing is achieved through atomic manipulation. The semi-technical explanation: electromagnetic fields propel ions towards the metal in a chemically inert gas such as Argon. Described as “atomic billiards,” this blast of ions dislodges groups of atoms in short bursts and spreads them evenly across the film’s surface.
Although dyed and metallic films are used in different situations, there are a few similarities between them. For instance, metallic films aren’t completely heat-proof as the ‘heavy’ metal particles tend to attract natural heat, while the heat-absorbing dyed films can’t help being slightly reflective.
The last type of window film is the hybrid, which contains metals and dyes. By blending these two ingredients together, the best qualities of both can be achieved with less of the negatives. The combination of gray dye and titanium is a great example of this. When gray dye is used by itself, the film would A good example is gray dye and titanium coating. If each were used alone, the dye would cause the film to darken dramatically, whereas the titanium would give the film a very mirrored look. But when both are combined using a small amount of each, you are left with a much brighter and less reflective film.
With hybrid films, the commonly-held belief that “the darker the film, the more heat-resistant it is” no longer holds water. In fact, most people choose darker films simply because they provide the best privacy.