The encyclopedia · Product & Design · Technical decision · 2001
Pilkington coated glass with TiO2 so sunlight and rain clean it themselves
A nanometre TiO2 layer breaks down organic dirt in UV and turns glass hydrophilic so rain sheets it away.
NSG Group (Pilkington)
the move
Windows on high buildings are hard and costly to reach, so dirt stays until a crew crane or cradle is paid to remove it.
Pilkington, part of NSG Group, laid a nanometre-layer TiO2 coating on the glass during manufacture, giving it a dual self-cleaning action rather than a manual one.
The layer is photocatalytic, breaking organic deposits down under UV, and hydrophilic, so rainwater runs off in a sheet and carries the debris away instead of leaving droplets.
why it works
- It converts a maintenance cost into a chemical reaction that runs for free every day.
- The coating reacts with UV, so it works hardest exactly where buildings are sunny and dirty.
- Hydrophilic sheeting removes dirt without streaking, which a hydrophobic bead would not do.
- It requires no extra power, chemicals or labour after installation.
what transfers
Use a cheap continuous input (light and rain) to do the recurring work you previously paid people to do.
what came after
Pilkington Activ, sold as the world's first self-cleaning glass, became a full product family including solar-control variants and was used in facades, skylights and conservatories; competitors followed with their own photocatalytic glass.
references
- What is Self-cleaning Glass?
- Photocatalytic degradation of soot deposition: Self-cleaning effect on titanium dioxide coated cementitious materials
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