Window films are manufactured by laminating several elements together in different configurations depending on the intended end use. There are 5 basic categories of film construction:
Clear Films - non-reflective because they don’t contain any metals. Used predominantly in safety films that are not intended for solar control purposes.
Dyed Films - although non-reflective since they do not include any metals, these films do provide both heat and glare control through solar absorption.
Metallized Films - provide a tremendous amount of solar control because they reflect an abundant amount of solar radiation.
Hybrid Films - offers high heat rejeciton with a non-reflective look by combining metallized and dyed layers.
Ceramic Films - made from ceramic Nano technology, they offer the benefits of dyed film with the high IR infra-red heat rejection.
Clear films are Non- reflective, because they do not contain any metals to block or reflect solar radiation, although they can offer UV protection if a UV inhibitor present during the manufacturing process. Clear films are mainly used as Protective film for safety and anti-graffiti purposes. Protective films are thicker in their construction than regular or solar control films, usually starting at 4mil and up.
Dyed films come in a variety of colors and are produced in one of two ways:
1. The dye is applied to the polyester film itself.
2. The dye is actually mixed into the laminating or mounting adhesive.
The preferred method; from a manufacturability, uniformity, and durability standpoint, is to apply the dye to the base film. This process avoids the complications associated with mixing adhesives and dyes, then applying this solids laden mixture to the base film. The darker shades have a different/higher solids content and that has an effect on the adhesive.
There are several product benefits associated with dyed films. For consumers, dyed films provide increase optical quality and clarity through strong glare control. For dealers, dyed films are still easy to shrink to the glass and, all things being equal, the dry out time is shorter than for a film with a metal layer.
It’s also important to note that dyed films are less effective in controlling solar heat gain because dyed films control heat by absorbing solar energy. After the film is “saturated” excess heat is released. Metal films reflect the solar energy, which is more effective. Additionally, the durability of the color in dyed films is not as good as metallized, tending to turn a purple as some of the dyes are destroyed by the constant bombardment of sunlight. Yes, tint on cars parked in the shade will degrade more slowly than those left out in full sun all the time.
The process of adhering metal to a polyester base film is called vacuum coating. This “metallized ply” is what gives the film its reflective properties and can be tailored by manufacturers to give varying degrees of solar reflectivity.
There are three types of vacuum coating techniques used in the window film industry today: vapor deposition, e-beam and sputtering. All three types are performed in an ultra low-pressure vacuum chamber. This section will help you understand the differences and advantages of each type of vacuum coating process.
Vapor Deposition Chamber
Metallizing Process I - Vapor Deposition
The process of vapor deposition involves heating a piece of metal to its boiling point and allowing the metal vapor to settle on a passing polyester film.
To start, a metal wire (typically aluminum) is fed into a heated tub causing it to melt. Because of the low chamber pressure, the melting point of the metal wire is far lower than it would be under normal conditions. When the metal wire finally boils, a vapor is formed which will adhere to a piece of polyester film passing through the chamber. The amount of metal applied to the film is determined by the speed at which the polyester film passes through the chamber. By adjusting speeds, the manufacturer can alter the density of the metal applied to the film. This allows the manufacturer to create multiple film bases with varying degrees of metallization. Generally speaking, the longer the exposure to vapor, the thicker the metal coating on the film.
Metallizing Process II - E Beam Deposition
This process is almost identical to the vapor deposition procedure except the metal wire is not placed in a heated tub. Instead, an electron beam is used to heat the metal wire. The benefit of this process is a wider variety of metals can be used because there is only one concentrated source of heat.
Metallizing Process III - Sputtering
The metallizing procedure known as sputtering is the most recent technological method of adhering metals to film. As in vapor deposition, a low-pressure vacuum chamber is used to create a gas atmosphere. Electrical energy is then used to create a negative charge to the gas molecules. The vacuum pressure allows the subsequent gas molecule particles to move freely and rapidly about the chamber. When these charged particles collide with a metal “cathode”, small particles of the metal are chipped off the cathode and subsequently deposited on the film. Similar to the vapor coating method, the speed at which the film travels through the chamber determines the density of the metal on the film.
Each vacuum coating process has its own particular benefits. Vapor and E Beam metallizing methods generally create a product with higher solar heat control. Plus, the curing process is quicker. The porous structure allows mounting solutions to evaporate easier resulting in a reduced period of film “haziness” and quicker dry out times.
A combination of dyed and metallized layers offering the best of both worlds in high heat rejection and non-reflective look. Hybrids in general last longer than a dyed film and are considered to be high performance films because of the solar control properties gained from the metallized layer.
Ceramic films are neither dyed nor metallized, and are created using a sputtered coating process. Titanium Nitride is sputtered onto a polyester film layer. The benefits include; long lasting films with high heat rejection properties that are visually beautiful.
The key ingredient is a unique chemical compound called Titanium Nitride [TiN], a tough ceramic material often used to protect and preserve machine tools. TiN contains exceptional infrared (IR) reflective properties, which allows the film to reject solar heat at a higher rate compared to traditional film products. Plus, TiN is extremely durable.