'Exciting' find for scientists watching paint dry

British scientists have been hard at work watching paint dry - and they claim the results are "exciting".

The University of Surrey researchers identified a previously unknown mechanism that could enhance a wide range of products, from cosmetics to agriculture.

They found that as paint dries, small particles team up to push away large ones.

But you have to look very carefully to see this happening.

Working with French colleagues from Claude Bernard University in Lyon, the scientists used computer simulations and experiments to show how coatings containing different-sized particles - such as paint - spontaneously form two layers.

Understanding how this happens could be used to control the properties of the top and bottom particles independently, thereby improving the performance of coating materials.

Sunscreens, for example, could be designed with a surface of sunlight-blocking particles and a bottom layer of sticky particles that adhere to the skin.

Team leader Dr Andrea Fortini said: "When coatings such as paint, ink or even outer layers on tablets are made, they work by spreading a liquid containing solid particles onto a surface, and allowing the liquid to evaporate.

"This is nothing new, but what is exciting is that we've shown that during evaporation, the small particles push away the larger ones, remaining at the top surface whilst the larger are pushed to bottom. This happens naturally."

The scientists, whose findings appear in the journal Physical Review Letters, are now looking at ways to alter the width of coating layers by changing the type and amount of particles.