Blog > Category > Posted: 2019-Jul-23, Updated: 2023-Apr-25
Yes, you can actually purchase windows that will do all the tough cleaning for you - no ladder, no buckets, no sponges… Self-cleaning windows will make you and your eyes happier by helping you conserve energy for all those “OTHER” house maintenance chores.
An organic grimy microscopic residue is naturally present on just about everything we see and touch, and on glass, it creates a hydrophobic repelling nature (oil and water effect) that causes water to bead into droplets that flow down the glass on windows. Loose dirt will build-up on these water beads and in microscopic channels that dry into dirty looking watermarks.
In 2001, Pilkington Glass announced the development of the first self-cleaning windows, Pilkington Activ™, a hydrophilic process. This coated glass has a visible reflectance of around 7% and a visible haze of less than 1% but absorbs 20% of incident solar UV light which is used in the self-cleaning process. The coating is robust and cannot be damaged by the application of tape or moderate cleaning. Pilkington claims that the coating will last the lifetime of the window frame. Using their own special patented processes other companies jumped on the bandwagon to produce their own versions of self-cleaning glass.
Through photocatalysis (UV energy) a safe and effective chemical reaction, a thin permanent coating of titanium dioxide (titania) about 20 nanometers thick on the glass burns away and breaks down the molecular bonds in a naturally forming layer of microscopic grim (organic dirt particles).
When it rains, or when a window is sprayed with water, the water will interact directly with the glass becoming hydrophilic (glass molecular structure attracts the water molecules) and forms a thin even sheet of water that carries dirt away allowing the glass to dry faster and cleaner.
Another method of keeping glass and other objects shiny and clean is through what is called a hydrophobic process, where a thin layer of silica coating is applied to the glass through nanotechnology. Windows are by their nature hydrophobic - this process makes them super-hydrophobic.
The hydrophobic process provides anti-smudge coatings and is very easy to clean. The hydrophobic process is the opposite of hydrophilicity, instead of spreading the water into a thin layer (hydrophilicity), its repelling nature prevents dirt bonds to the glass, allowing for easy cleaning. However, because hydrophobic windows typically drip and dry in beads, they still need to be carefully rinsed to prevent dirt from drying in place.
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