"The photocatalytic paints and plasters that have just come onto the market include nanocrystalline material thanks to which the consumer sees a cleaner wall and breathes fresher air," say Visa Vehmanen, a researcher at Kemira Oy.

Kemira Oy produces photocatalytically active nanocrystalline titanium dioxide that can be used as a raw material in self-cleaning paints and plasters that also clean the air.

Photocatalytically active titanium dioxide can decompose organic substances into carbon dioxide when it absorbs light. A photoactive paint surface decomposes dirt from its surface and harmful substances, like nicotine, from the air," Vehmanen explains.

Old becomes better

The opaque titanium dioxide crystal traditionally used in paints is more than 200 nanometres in size. The photocatalytically active titanium dioxide crystal is about 20 nanometres. The smaller size makes greater photocatalytic activity possible.

"With research methods based on nanotechnology we have a better understanding than before of what happens in the production process of titanium dioxide. When we understand the process thoroughly, we can affect the properties of products on a nanometre scale and make better products."

Nanotechnology is, according to Vehmanen, a means of obtaining better products from old ones. On the other hand, nanotechnology makes it possible to develop completely new applications.

"Nanotechnology is one part of the rapid technological development. From the consumers' perspective the most important thing is how the product works. Whether there is a new property in a product thanks to nanotechnology or not is of hardly any significance to the consumer," Vehmanen states. "Users of photocatalytic paints and plasters are still few in number, but usage is growing all the time."

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A photoactive paint surface decomposes dirt from its surface and harmful substances, like nicotine, from the air.