Self Cleaning Glass: What makes it different from 'Easy Cleaning Windows'...

Source Post: http://www.replacement-windows.com/windowbb/viewtopic.php?t=2101

Window glass described as “self-cleaning” has a special photo-catalytic coating - titanium dioxide - applied to the surface. The titanium dioxide coating makes the glass surface hydrophilic which means that water will sheet and flow off the glass.

As a comparison, most after-market coatings (such as Rain-X) are hydrophobic which results in the coated glass surface repelling water causing it to bead up on the surface. A hydrophobic coating will leave dirt and mineral deposits (spots) behind when the water evaporates whereas a hydrophilic coating results in a surface layer of glass that is “slippery” to water which then sheets off carrying the dirt along with it.

In addition to being hydrophilic, the titanium dioxide coating chemically reacts with the ultraviolet rays in sunlight to oxidize organic material on the glass. This process, called photo-catalysis, breaks down dirt and other organic materials and prevents them from sticking to the glass. It works on organics, but the coating does not break down inorganics.

Some of the folks that produce glass with the titanium dioxide coating like to say that their glass is self-cleaning (Pilkington, PPG), whereas some manufacturers (such as Cardinal, Guardian) avoid the term “self-cleaning in favor of “easy cleaning” which is probably a bit more understandable.

While the difference between “self-cleaning” and “easy-cleaning” might be considered to be trivial, there is some concern in the window industry that eventually glass with the titanium dioxide coated glass will need to be cleaned – even if it is simply a matter of spraying the windows with a garden hose – which will lead to grumbling from consumers about being mislead by the “self-clean” description. .

till, this is a very nice add-on product and it does work as advertised as long as people realize that “self-cleaning” requires sunlight and an occasional wash-down with water – be it rain or a garden hose – to remove whatever debris might be on the glass surface.

Source Post: Self Cleaning Glass Anyone?
http://www.replacement-windows.com/windowbb/viewtopic.php?t=2101
Posted: Mon Oct 15, 2007 8:02 pm Post subject: self-cleaning glass