Understanding different types of Window Tint Films

All window tint films start with the film, which is always polyester, 2 to 7 mils thick. Quite often, several thin layers of film are bonded together. One side is coated with either a pressure-sensitive or water-activated adhesive. The exposed surfaces of most window tint films are also treated with a hard, scratch-resistant coating.

To filter out ultraviolet radiation, chemical UV blockers (cyclic imino esters) are incorporated. If the window tint film's purpose is to provide only UV protection and shatter resistance, no other materials need to be added.

Below is a technical breakdown of the components that make up various window tint films.

KEY POINT by tintingaustralia
"Hybrid films are often referred to in the market place as Carbon, Ceramic, Titanium etc these are your premium window tint film choices for your car, as they last the longest and provide the highest level of heat, glare and UV rejection. As you see below they are more complicated to construct which is why they cost more than a much simpler dyed film construction."

Dyed Window Tint Film

 

From there, three separate technologies are applied to achieve different performance characteristics. The first is simply a dye, which absorbs heat. Because most window tint films are applied to the inside surfaces of windows, it's easy to imagine that the absorbed heat would disperse indoors. In fact, the heat rejected by the window tint film is stored largely in the glass, and is drawn away by external air movement. A tiny percentage does bleed inward, but because the average speed of external air movement is so much greater--the daily average is 15 mph, versus 1/2 mph indoors--the ratio is 30:1 or better in favour of outdoor heat dissipation. Because double-glazed windows don't allow air movement between panes, interior-dyed films should not be used on thermal glass.

The other two processes, called deposition technology (vacuum coating/metallizing) and sputtering technology (advanced metallizing), deposit a layer of metallic particles on the film, giving it a reflective coating. In each case, a second layer of film protects the coating. Metallized films reject heat by reflecting it before it can be transferred through the glass.

Dyed Window tint film

Deposited Window Tint Film

 

In deposition technology, the film is drawn through a tank containing metal ingots--usually aluminium or nickel-chrome, and occasionally copper. A vacuum is created by reducing the pressure in the tank, which is then flooded with argon gas and the ingots are heated. The heat causes the metal to give up particles that migrate to the film's surface. The density of the metal deposition is controlled by the speed of the film through the chamber.

While deposition technology works well and is relatively inexpensive, it has its limits. To be effective, the metallized coating must be fairly thick, as the particles are comparatively large. What this means at a practical level is that it produces a darker, more highly mirrored surface. And second, the list of metals that can be deposited evenly is fairly short, which means fewer product options.

 

Sputtered (Advanced Metalizing) Window Tint Film

 

Sputtering technology is more complicated. Sputtering is also done in a vacuum chamber, but the metallizing is achieved at the atomic level. In brief, electromagnetic fields direct streams of ions from a chemically inert gas (usually argon) toward the metal. This ion bombardment, which is often described as "atomic billiards," causes groups of atoms to dislodge in small bursts and scatter uniformly across the film.
The practical benefits of sputtering are that 25 to 30 different metals can be used and the metallized coating is much lighter. It's possible to sputter metal in a layer one-hundredth the thickness of a human hair. Different metals are chosen to subtract specific bands of radiation from the solar spectrum. The result is a highly reflective layer with very little mirror effect, heat absorption or colour shift. Because sputtering is more expensive, these films occupy the high end of the price range. Metallic films control radiation through reflectivity. Simplified film consists of polyester layers, metallic coating, adhesive and scratch-resistant coatings.

While the performance characteristics of dyed and metallic films are generally distinct, there is some overlap. Heat-absorbing dyed films are somewhat reflective, and metallic films do absorb some heat because of the mass and colour of the metals involved.

Metalised Window tint film

Hybrid Window Tint Film

 

To further complicate the issue, many films contain both dyes and reflective metals. By combining dyes and metals, the negative effects of each can be reduced without sacrificing performance. A good example is grey dye and titanium coating. If used alone, dye would darken the film significantly, while the titanium would produce a highly mirrored surface. When paired, less of each can be used, resulting in a film that is relatively bright and non reflective.

This point is significant, if only because it quells the notion that the darkest films reject the most heat. In most cases, dark films are chosen because they offer greater privacy.

 

Hybrid Window tint film