Beneath the Surface: The Truth about Self-Cleaning Glass

Around 5 years ago the British glassmaker Pilkington launched what has long been regarded as the ‘Holy Grail’ of the industry: glass that actually keeps itself clean.

Think of the possibilities! Tall glass edifices lovingly created in the favourite building material of architects,maintained throughout their lives as gleaming jewels; buildings of all shapes and sizes designed without any curb on creativity imposed by the prosaic demands of maintenance; and significant reductions in costs and disruptions caused by the otherwise simple task of window cleaning.

Pilkington has a long and proud history as one of the world’s great innovators: with a long list of inventions, many of which have impacted way beyond the mere conservations of the glass industry. The company conceived and developed the ‘float’ method by which 95% of the world’s flat glass is manufactured today. So it was fitting for Pilkington scientists to create Pilkington Activ™, the world’s first self-cleaning glass.

Does it really work and if so,how?
The principals are relatively simple, the difficult bit being the application of the coating during production of the glass.A coating called titanium oxide – a harmless whitening agent found in many household products including paint and toothpaste – is deposited on the surface of the glass in an incredibly thin layer during manufacture of the glass.

The coating is of course totally transparent (another clever bit) and is permanent and remains active for the lifetime of the glass. The way it works is also relatively simple: the coating is ‘charged’ by ultra violet light drawn from ordinary daylight, with which it reacts to biologically, breaking down any organic material deposited on the surface of the glass, such as bird droppings, tree sap and so forth. This it does over a period of a few days in a continuous cycle.

The second process created by the coating is that it causes water – rainwater usually, or perhaps from a hose in drier periods – to ‘sheet’ evenly across the surface, unlike the usual beading effect on ordinary glass. This has the effect of washing the surface of the glass and of course taking with it the dirt. It will even remove inorganic material that may have layered itself onto the organic matter.

So, yes, it really does work: windows installed with Pilkington Activ™ self cleaning glass – and the one other product that uses this technology – will remain cleaner and brighter and require little if any additional cleaning. For most of us the simple elimination of the chore of window cleaning as we know it, is enough.

Are there any other glasses that will keep themselves clean?
Only glass that is manufactured with a permanent coating of titanium oxide offers the dual action continuous cleaning process as described here. In the wake of the success of Pilkington Activ™ there are a number of other ‘easy-clean’ glass products now offered that make various claims, many of which are spurious and which must be considered with care. The usual benefit of specifying such products is price, simply as by definition they cannot offer the cleaning performance of titanium oxide-based products.

Inevitably they use a coating that is sprayed on after the glass has been manufactured and which, by definition, has a limited life sometimes of just a few months dependent upon the application and treatment of the product. Using these criteria, it is a simple choice to make.