Volume 16, Issue 3 - May/June 2012


Back to Basics:
Peeling the Onion
A Look at the Components of Window Film and How They Work
by Katie O'Mara

There is so much more to window film than meets the eye. On the surface it appears to be a shaded piece of plastic that sticks to windows. Yet, beneath the surface lies layer upon layer of complex materials that work together to keep out harmful ultraviolet (UV) light, glare and heat.

Recap: Lesson in Light
In the first installment in our series we discussed how window film works and achieves the benefits that it does. When the three components of solar energy—UV light, visible light and infrared light—hit a surface they will either reflect off of the surface, transmit through the surface or be absorbed into the surface. Window film is used to regulate the amount of energy that is either absorbed or transmitted and reflect that energy away. The more energy that film can reflect the more energy-efficient it will be.

The components that make up film help with this process of reflection which is why it’s important to understand the components and why they are a part of this product.

Layer Low-Down
Window film consists of a series of different layers of film. Different manufacturers may use different ingredients and different additions, but the basic recipe for window film generally remains the same. On the glass side of the film the first layer is the protective liner that ensures that the adhesive layer is protected until the film is ready for installation. This liner, while not important once film is installed, does play an important part in protecting the adhesive and ensuring that it bonds as well as possible.

The adhesive layer will affix the film to the window and keep it in place. Different films will have different “stick-ability.” Some may have low adhesion, in order to be removed and place in a different spot. Others will have a high adhesion to allow the film to stay in place longer. The adhesive is very important to the effectiveness of the film and if it were to be faulty the installed film would fail.

Next in the layers of film is polyester. This is the “meat and potatoes” of film. Some films will have multiple layers of polyester with adhesive on top of the initial polyester layer. The polyester layer is where you see a lot of additional add-ons like metals and dyes that can give film different properties.

Many films will also have a scratch resistant acrylic coating that is placed over the polyester to protect the film from scratches or tearing. These have grown a lot over the years and new technology is consistently released to ensure less scratches. These are important to maintain a distortion-free viewing area and allowing the glass to look at natural as possible from the inside.

Combined together, these layers create the base for most window film products. As the industry grows and trends change the different types of available window film become more complex and more powerful.

Manufacturing Materials
Once the ingredients for film reach the manufacturing floor the processes that film undergoes can vary. Laminating occurs when two layers of polyester are bonded together using an adhesive. Glass laminating film can be used to create for secure buildings in the event of break-ins, storms and other unforeseen dangers. Metallizing, another common process, involves evaporating metal on the surface of the film. Similar to metallizing, sputtering involves knocking atoms of metal onto the film surface. A variety of metals can be used for sputtering and these films commonly are used due to reflective properties.

Dyeing film is another popular process for manufacturing. This varies between different manufacturers and most keep their process of dyeing film fairly secretive.

As we continue to see products changing and technology growing, consumers will need to stay educated on what products can give them what they need. Understanding the basics, like the recipe for film, can help dealers better present and sell the product to consumers, designers and architects. Not only can it make a company appear professional, but it can also bring in that extra sale.

Katie O’Mara is the editor of Window Film magazine. She can be reached at komara@glass.com, follow her on Twitter at @windowfilmmag or on Facebook by searching for Window Film Magazine.

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