Researchers study the mechanics of drying paint

SURREY, England, March 18 (UPI) -- Researchers in England and France are watching paint dry -- for science.

Specifically, the research team wanted to understand how particle size affects the mechanics of drying paint and other coatings. Their research showed that coatings with differently sized particles solidify spontaneously into two layers.

By manipulating the size of the particles in paint, researchers were able to change the qualities of each distinct layer. The findings -- detailed in the journal Physical Review Letters -- have implications for a variety of coatings and industries, from beauty products to pharmaceuticals.

"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," lead study author Andrea Fortini, a material scientist at the University of Surrey in England, said in a news release. "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."

Particles could be manipulated to improve sunscreens, Fortini said.

"Most of the sunlight-blocking particles could be designed to push their way to the top, leaving particles that can adhere to the skin near the bottom of the coating," he explained. "Typically the particles used in coatings have sizes that are 1000 times smaller than the width of a human hair so engineering these coatings takes place at a microscopic level."