In a finding that is sure to add to one of the longest-running debates in music, a detailed analysis of the varnish on five instruments made by Antonio Stradivari reveals that he coated the wood with a rather humdrum mix of oil and resin. Those looking to the varnish as the secret to the master Italian violin maker’s renown, the study suggests, had best look elsewhere.

“It’s a very basic recipe,” said Jean-Philippe Échard, a chemist at the Musée de la Musique in Paris, who, with other researchers in France and Germany, analyzed tiny samples of wood and varnish from the museum’s Stradivarius collection, four violins and a viola d’amore dating from 1692 to 1724.

Their study, published online on Thursday by a German chemistry journal, Angewandte Chemie International Edition, found that a drying oil, linseed or walnut, was used as a first coat to seal the wood. That was followed by a coat of oil and pine, fir or larch resin, with red pigments added in all but the earliest instrument. The recipe was probably little different from that used by others in the town of Cremona. “The ingredients were simple, so probably the skill was in his hand and eye,” Mr. Échard said.

In the centuries since Stradivari’s death, musicians, critics and luthiers — makers of stringed instruments — have debated what gives many of his 600 known instruments their brilliant tone. Perhaps it was the wood he used or the patterns he developed, which are widely copied today. Or perhaps, some suggested, there was a secret ingredient in his varnish — egg or animal-hide proteins in the base coat, and amber, myrrh or some other more exotic substance in the top coat — that stiffened the wood just so.♣

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