The violin case

It won't necessarily be music to the classical purist's ear, but chemists have been instrumental in revealing the secret beneath the varnish on a Stradivari violins, and the secret is: there is no secret.

Antonio Stradivari is perhaps the most famous instrument maker of all time. He is especially celebrated for his violins, which he made in Cremona circa 1665 till his death in 1737. The "legendary" varnish on his instruments has fascinated musicians, violinmakers, historians, and others ever since and has led to repeated speculation that there was a secret ingredient that endowed a Stradivari violin with its unique and beautiful tone.

Now, European researchers have taken minute samples from carefully selected parts of five violins and subjected them to microscopic and spectroscopic analysis. Although the different instruments were made over a period of three decades it turns out that their varnishes are all very similar. It is only the red pigments that seem to vary through Stradivari's career and, for those listening in black and white, the colour of a violin has no aural impact.

The team, led by Jean-Philippe Echard of the Cité de la musique, Musée de la musique, in Paris and Loïc Bertrand of IPANEMA Synchrotron SOLEIL, in Gif-sur-Yvette, Franc, working with colleagues there and at the Institute for Analytical Sciences, in Dortmund, the LC2RMF and CRCC, and the LADIR, in Paris, the University Pierre et Marie. Curie, in Paris, and the Staatliche Akademie der Bildenden Künste, Institut für Technologie der Malerei, in Stuttgart, Germany, studied the constituents of the varnish samples. The only ingredients they found in the Stradivari varnishes were composed of well-known materials used in decorative arts and paintings from the period. There is, it seems, no legendary ingredient, the chemists say.
The Stradivari violins examined have been in the collection of the Musée de la musique for at least a century: one a "Long Pattern" model, possibly circa 1692, the "Davidoff, dated 1708, the "Provigny" from 1716, (a cross-section of the varnish with the wood at the bottom is pictured here), the "Sarasate" from 1724, and the head of a viola d'amore, dated from around 1720.

"Although the five instruments were produced over a period of three decades, their varnishes are very similar," says Echard. "Stradivari first applied a layer of an oil comparable to the oils used by painters of the same epoch, without fillers or pigments to seal the wood. We did not find a mineral-rich layer, as some earlier work suggests. The master violinmaker next applied a slightly tinted oil-resin layer. We have detected nothing that would have suggested the use of protein-containing materials, gums, or fossil resins."

The team found no pigments in the outer layer of the "Long Pattern" model although in earlier examinations, they saw the red pigment vermilion in the varnish of the "Sarasate". Now, they have found two additional red pigments in Stradivari's varnish: red iron oxides and a lake pigment made of an anthraquinone dye, probably cochineal, on an aluminium oxide substrate. The use of different red pigments allowed Stradivari to give his instruments a variety of beautiful hues, to enhance their appearance but there is no secret sauce in the Stradivari varnish.

"At first, I was surprised by this news," says Tim Lihoreau, Creative Director of Classic FM, "I'd always heard that it  was something in the varnish that made Strads so special - the  vintage Rollers of the fiddle world, as it were. Having said that, in many ways it only adds to the mystique of the Cremonese creator - that, in  some 'weird science' way, it's his magic art that is the key: a blend of all his crafts, coming together to make such legendary instruments."