At first glance, "self-cleaning window" seems an oxymoron. But to the delight of many homeowners, there's nothing at all odd about window glass that sheds rain - along with dirt and grime - like water off a duck's back.
"Consumers at first didn't find the concept of self-cleaning windows very believable," says Lisa Detwiler of PPG, manufacturer of SunClean glass. "But after they'd seen the window glass in action, they totally changed their minds."
As with many low maintenance products, technology plays a hand in this miracle glass.
Detwiler says a light-sensitive coating of titanium dioxide is fused into the glass. The UV rays in sunlight activate the coating - a process called photocatalysis - to discourage any particles from tightly adhering to the surface. The coating also has hydrophilic properties (translation: water sheets off rather than beads) to carry the particles away. This minimizes spotting and streaking.