Fun's in watching paint dry

By Damon Shorter

Contrary to popular belief, watching paint dry can be a fascinating and extremely lucrative pastime.

Ask one group of ANU chemists which has turned its academic know-how to what is widely touted as the most boring activity in existence.

Over the past five years the group, headed by Professor Ric Pashley, has been investigating exactly how paint does dry, at a molecular level - under the watchful eye of multinational paint and chemical company Rohm and Haas, which has given almost half a million dollars to the project.

"Watching paint dry is actually quite fascinating if you study it at the molecular level," Prof Pashley confesses, and he says the company's investment is beginning to pay off.

"Very quickly when you start doing basic research like this you begin to see commercial applications," says Prof Pashley, who became involved in the project through his expertise in colloid chemistry, which studies how microscopic spheres interact with one another.

The chemistry of paint falls neatly in his field of expertise because paint is an even mixture of water and tiny blobs of soft plastic similar to perspex. Without additives, paint dries to form a completely clear film, Prof Pashley explained, but various clays and pigments are added to give different colours.

As paint dries, water evaporates and the plastic spheres (or colloids) are forced together, fusing to form a thin layer of plastic that gives the paint a smooth, shiny finish.

Below a certain temperature though - about seven degrees - the plastic colloids do not fuse properly and the paint becomes flaky.

This is where the ANU chemists step in. PhD student Marilyn Karaman with Prof Pashley and Prof Barry Ninham have designed a machine to measure precisely what this crucial temperature is, triggering a small revolution in the billion-dollar international paint industry.

An international patent for the machine has recently been filed in the US by Rohm and Haas and Prof Pashley estimates 500 machines could be sold worldwide at around $100,000 each. All the machine needs now, he says, is a catchy name to replace its mundane working title: Minimum Film Formation Temperature Instrument.

Their work is a good example of how industry can benefit from a small outlay, he said. "Rohm and Haas originally approached us to do this sort of research for them. They had the faith to try that and now it has paid off."