Can glass really be self-cleaning?

(NC)—Today, there are many glass coatings being sold with descriptive names such as “self-cleaning” and “easy to clean”. These coatings are most often applied by the glass manufacturer and designed to be on the external surface of your windows.

David Mitten, the executive director of Sawdac's Window Wise program explains: “Self-cleaning glass does not make your window clean. What it does is two-fold. First, it makes the glass in your window less dirty than it would be if you weren't cleaning it regularly. Second, it makes the glass easier to clean

The characteristics of these high-tech coatings that facilitate self-cleaning are called “hydrophilic” and “solar activated”, Mitten points out.

Hydrophilic glass has had a coating added to it that makes the surface smoother and less sticky. Dirt doesn't adhere well to hydrophilic glass and rain water tends to spread out evenly.

Solar activated glass has had a coating applied to it that stores light energy from the sun in its electrons. This excessive energy forces the electrons to a less stable outer orbit. When rain water hits the energy is released returning the electrons to their original, stable orbits. In this process extra oxygen molecules are created which act as an emulsifier on dirt particles, causing them to fall away or be washed away from the surface of the glass.

The term “self-cleaning glass” does not mean that your windows, if left un-cleaned by human hands, will be as clean as if they were, says Mitten. It means that, on their own, they will simply be less dirty. If you never wash your windows, and would like them to be naturally cleaner, this glass is for you.

Also, it is possible to damage these coatings, he says. “Do not clean glass with a hydrophilic coating or a solar-activated coating with anything metallic or hard enough to scratch the glass.”

For more information please visit www.sawdac.com.

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