300-year-old secrets of

Stradivarius

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Stradivarius violins can cost 2 million. Does their sound match their price? Julian             Brown asks what a 17^th century craftsman knew that modern instrument makers are only just discovering.

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Antonio Stradivari was born in 1644, into a respected family of craftsmen in Cremona, a northern Italian town that was already famed far afield for its violins.

Stradivari was apprenticed to the instrument maker Nicole Amati at around the age of 12 and by the time he died, aged 93, he had made around a thousand violins and at least 300 other stringed instruments, including cellos, lutes and guitars.

A productive life, certainly, and a reasonably well-rewarded one: he sold most of his output for the equivalent of around 4 each, and appeared well satisfied with the moderate, middle-class income and lifestyle his craft brought him and his family. Stradivari could never have dreamt that, 250 years after his death, his violins are auctioned and reach prices anywhere from 200,000 to several million.

'What makes a Stradivarius violin so valuable? That's a question that continues to intrigue musicians, scientists and the public to this day. For decades, scientists and violin makers have tried to establish the Stradivarius's "secrets".

During his career, Stradivari made certain subtle changes in the proportions of the violin, gradually increasing the instrument's power. While his early work followed the traditions of his teacher Amati, by the close of the 17th   century the Stradivarius had become flatter and broader and the bridge began to look much as it does today.

But violin makers have long copied the proportions of Stradivarius's instruments without achieving the same results. So the secret must He elsewhere. But where? In the deep, lustrous auburn-reel varnish, according to one theory. But there's a problem. Strads have withstood nearly 300 years of wear and tear. Not surprisingly, the rich varnish on many of them has taken a battering and, in some cases. Most of it has been worn away. Vet these instruments still sound magnificent,

In the- 1980s a US researcher came up with a new theory: the secret lay in the wood. Stradivari used wood - maple and spruce -that was delivered to Cremona by being floated along the Italian canals: perhaps the contact with water had changed its character. The idea was initially supported by electron microscope pictures of the violin's surface: Strad wood was found to be riddled with tiny, open pores, while those of modern instrument's were tightly closed.

But later research suggested that whether the pores showed as open or closed under examination was not dependent on the violin at all but rather on how the wood sample had been cut and prepared before it was examined under microscopy,

Electron microscopy, however, may yet provide the answer. Recent research in Cambridge has found a layer beneath the Strad's famed varnish. Under the electron microscope it appears like a seam of marzipan sandwiched between the cake of wood and the icing-like varnish. Claire Barlow and Jim Woodhouse, who work in Cambridge University's Engineering Department, were able to obtain a few small samples of wood taken from Strads and other old instruments that were undergoing restoration. They subjected the middle layer to spectroscopic x-ray analysis to find out what it contained. The results varied from sample to sample, but they all contained a range of minerals including aluminium, silicon, phosphorous and calcium.

This turns out to be consistent with another idea put forward in the 1980's. For some time experts had been arguing over whether the crafts en of Cremona had used some kind of wood sealant before applying varnish to the instruments they were making.

John Chipura, an American geologist and violin enthusiast, published a letter in the magazine The Strad suggesting that this sealant may well have been a layer of Roman cement. Readily available, the cement was made from local materials including volcanic ash, whose mineral constituents are-very similar to those revealed by Barlow and Wood house’s spectroscopic analysis.

Even so, Barlow is reluctant to draw any firm conclusions about the purpose of the layer. "It's tempting to think that it might have been applied as a sealant, or to provide a smooth surface on which you could varnish easily. But these layers are much thicker than you'd need to do either of those things. They were put on for some purpose that we still don't really understand."

Barlow's collaborator Jim Woodhouse, has spent many years studying the acoustics of violins and he was interested to find out what effect the mineral layer would have on the sound quality of the instruments.

"Virtually any treatment of the wood, such as a preservative or varnish, will change the vibrational properties of the violin and therefore its sound," he explains. "We have taken flat plates of spruce and varnished them with various combinations of finishes, but the differences in the vibrational properties we found were really rather subtle. So there may be an effect, but it's not immediately obvious."

Undoubtedly Stradivari was a supreme craftsman, but the secret of his genius may not lie in one aspect of his craftsmanship but in a combination of factors. "To make a violin you've got to do a great many things right and in harmony with one another," says Woodhouse. "if there is a secret to the Stradivarius sound, it is in achieving a perfect balance."