Self-cleaning Glass

Old 05-18-06, 02:27 PM
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Self-cleaning Glass

Does anyone have experience with self-cleaning glass (Pilkington Activ Slef-Cleaning or PPG SunClean)? Does this stuff really eliminate window cleaning? How does the cost compare with regular clear glass? Thanks.
Old 05-18-06, 06:18 PM
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What you are looking for is not Pilkington Activ, it is little gnomes that run around and clean glass. After googling the site, I see where the coating tends not to have organic dirt adhere to its surface (didn't say anything about inorganic dirt), and it has to rain to clean the glass, so you are still stuck with the little gnomes cleaning the inside of the glass where it doesn't rain. They wouldn't even consider pricing the stuff, and when someone has a product that "if you have to ask, you can't afford it", I steer clear.
But to your question, no experience, and probably won't.
Old 05-20-06, 06:05 AM
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Self cleaning glass

Basically, there are two different types of glass on the market described as either self-cleaning or easy cleaning.

-- Self-cleaning glass has a special photo-catalytic coating applied to the surface of the glass...actually nitrogen enhanced titanium dioxide.

-- Easy-cleaning glass on the other hand has a coating of silicone dioxide or essentially a glass layer on the glass.

Both coatings are hydrophilic which means that they "like" water, which sounds odd at first glance, but a hydrophilic coating will cause water to sheet and flow off the glass. A coating, such as Rain-X, is actually hydrophobic which means it doesn't like water and because it repels water, a hydrophobic coating will actually cause water to bead up on the glass which means that it will leave dirt and mineral deposits behind when the water evaporates.

Conversely, hydrophilic coatings actually make the glass really slippery and water slides right off carrying the dirt along with it.

The primary difference between the two types of hydrophilic coatings is that the titanium dioxide version 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 actually works, but please note I said organic molecules. The titanium dioxide coating does not break down inorganics.

The folks that produce glass with the titanium dioxide coating (Pilkington and PPG) like to say that their glass is self-cleaning while the folks that produce glass with silicone dioxide like to say that their product requires less cleaning.

Unlike the titanium dioxide coating, the silicone dioxide coating does not react with the sun to break down the organics.

Ultimately, there is some concern in the industry about the term self-cleaning. There is concern that eventually, even the titanium dioxide windows will need to be cleaned because of a build-up of inorganics, both from exterior sources, such as "dirt" in the air and even minerals in rain or home-sprinkler water that will build up on the glass. This is especially true if the homeowner sprays off the windows with a garden hose and the homeowner has hard water.

Either way, both are pretty good products and both will very much make window cleaning easier...but the term self-cleaning is a bit misleading and there is actually a bit of trepidation in the window industry concerning the use of "self-cleaning".

Some window manufacturers are a bit concerned that if consumers are not happy with glass labeled as self-cleaning then the industry as a whole will look bad while others whole-heartedly endorse the concept of "self-cleaning".

Which brings us to the next generation of titanium dioxide coating.

The original "self-cleaning" glass titanium dioxide coating is applied to the surface of the glass during the float process. What that means is that the coating is applied while the glass is still partially molten during the glass manufacturing process.

There is now a version of titanium dioxide coating that is applied as a "sputter" coat in a glass-coating vacuum chamber.

This new version of the self-cleaning coating is said to be much smoother than the original and is actually applied to one side of a glass lite while a LowE coating is applied to the other side of the lite.

Currently, the only company in the industry that is offering the new coating is Andersen in their new "LoE4" product line.
Old 05-20-06, 12:36 PM
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Still need the gnomes to clean the inside, and you need rain to hit the outside, so if you have a deep overhang you will still have to wash the windows. Theory is fine, but practicality for a residence, I don't know....

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