Bubbles burst the best efforts of watchmakers

Giorgio Margaritondo reveals the bubbles responsible for defects on metal plating. EPFL

Researchers in Lausanne have discovered what causes tiny defects on metal plating used on cars, watches and all manner of metallic objects.

The culprits, it turns out, are bubbles of gas which form during the metalisation process. The metal is deposited on these bubbles, which vanish more or less instantaneously, leaving tiny imprints which are the origin of plating defects.

The team of Swiss and Asian researchers – working with the Federal Institute of Technology in Lausanne – discovered the process using a newly developed radiology technique, which enabled them to observe processes taking place at microscopic levels.

“It’s the first time we have been able to observe – at a microscopic or even smaller scale – the formation of metalisation defects,” said Giorgio Margaritondo, head of the Institute’s science faculty.

Filming at microscopic levels

He added that the observations were possible because the technique enabled researchers to film the process “in real time” by capturing images at a rate of 40 milliseconds per frame.

The discovery is likely to have major implications for industry, particularly jewellers and car manufacturers, who have long been aware of the metal plating defects but at a loss as to how to prevent them.

“By changing the metalisation conditions and directly observing the results, it is henceforth possible to minimise the defects due to bubbles,” said Margaritondo.

However, he is convinced that the new technology has wider implications in fields such as medical diagnostics.

“This technique is to radiology what a laser would be to a reading light,” says Margaritondo.

The new technique is staggeringly precise – it can detect objects at the level of a micron (one millionth of a metre) using x-ray imaging.

Margaritondo believes that if these rays could be concentrated – rather than being scattered as they are at the moment – doctors would be better able to view the inside of the human body using beams of lower intensity.

swissinfo