Let science and nature clean your windows!

There’s good news for those who hate spring cleaning chores – a new kind of glass that cleans itself and spells "goodbye" to frequent and laborious window washing.

Scientists at Pilkington, the world’s leading glass company, have now perfected a revolutionary new hi-tech glass called Pilkington Activ™. This is the world’s first glass to use natural daylight and rain to clean itself – without the cost to your pocket (or the environment!) of detergent or other chemical solutions.  The secret of Pilkington Activ™ is a virtually invisible, dual-action coating which uses the weather to make the glass clean itself. It does this in two ways:

First, it is photocatalytic: UV rays, abundant on even the cloudiest of days, cause the glass to react chemically with dirt and organic deposits, breaking them down and loosening them from the surface of the glass.

Secondly, it is hydrophilic: it attracts water, which slides down and off the surface of the glass without forming into separate droplets. This ensures that loose particles of dust and dirt are easily washed off during normal rainy weather.

Since the photocatalytic activity is continuous, even stubborn deposits, such as bird droppings or tree resin, will eventually be broken down and slide off the glass. To help things along in periods of little or no rainfall, the glass can simply be hosed or sponged off using clean water.

Pilkington Activ™ is being made available through selected suppliers in the form of double-glazed units for replacement windows or new homes.  All glass units incorporating Pilkington Activ™ have the Pilkington Activ™ hologram on the coated surface. When installed, the hologram is on the external face of the window.

How does it work?

The key element of Pilkington Activ™ self-cleaning glass is a microscopically thin, transparent coating of titanium oxide. Knowledge of the properties of this compound in relationship to glass has been widely available for as long as 20 years. However, it is the on-line application of the coating that has been perfected and patented by Pilkington technologists. This coating is bonded permanently to the surface of the glass on-line during manufacture of the glass. The overall thickness of the coating, which has several distinct chemical layers, is around 50nm (50 millionths of a millimetre), and is virtually indistinguishable in appearance compared to standard glass. The coating contains harmless chemical substances already found in the home, in such things as toothpaste and paint. In fact, with only small amounts of cleaning agents needed, Pilkington Activ™ is kinder to the environment than ordinary glass.

The ‘photocatalytic’ effect

This is the name given to the chemical reaction involving UV rays from natural daylight, oxygen and the special coating on Pilkington Activ™ that breaks down and loosens organic dirt particles from the glass. After an initial "running in" period of several days, UV radiation absorbed during daylight hours is sufficient to ensure that the necessary chemical reactions continue through the night.