By Clifford Hall | From the January-February 2023 issue of Strings magazine
Much has been made over the “secret” varnish recipes of historical Cremonese violin makers, especially that of Antonio Stradivari. Take, for example, this column, titled “The Fiddle-Maker’s Secret,” from Popular Science in its May 1929 edition, in which editors claimed “reports from Rome telling of the discovery of papers written by Antonio Stradivari… set the world of musicians on edge in anticipation of the revelation of the secret of Stradivari’s varnish… If the secret of the varnish that Stradivari used could be discovered, violin makers believe, new instruments equaling these old masterpieces in tone could be made today.”
The strings trade is a field of great variety—there are so many roles, passions, and stories. Tales Of The Trade shines a spotlight on the trade and the people involved in the art of the instrument.
The key to any instrument’s unique voice—old or new—is, of course, more complicated than the components of a maker’s varnish, and Dr. Georg Kremer of Kremer Pigmente suggests the historical varieties are likely not as mysterious as you might think. Celebrating 45 years of making violin varnish and other products for luthiers and artists, Kremer has spent a lifetime crafting products that faithfully recreate the past.
“Our research in old recipe collections gave us a lot of knowledge about the use and the production of historical materials. With this knowledge, we have been able to continuously improve production,” says Kremer. “We do hundreds of historic pigments, and for the varnishes of violins, we achieved the reenactment of more than 12 different madder lakes for more historic variety.” [Madder lake is an ancient reddish extract made by boiling the roots of the madder plant.]
This impressive assemblage of offerings is the direct result of decades of work. Starting in 1975, Kremer received a request from a friend, an English conservator in search of “smalt,” an intense blue pigment made of cobalt-containing glass, which was not available anymore at that time. The pigment was likely used by the ancient Egyptians and can be found in European oil paintings, particularly from the 16th and 17th centuries.
“It was the best pigment for fresco painting. After extensive research, I was able to reproduce [the recipe] forthe historic blue glass. With this innovation, my one-man company started in 1977 in Rottenburg am Neckar, Germany,” says Kremer. “[Since then], ongoing research and the production of old and forgotten pigments have allowed me to combine my chemical knowledge with my passion for historical products.”
This painstaking approach stands in stark contrast to the work of most commercial varnish producers. Kremer sees this change due to market forces. “In the second half of the 20th century, the distribution of paint materials changed. Easily available raw materials vanished in the market and got replaced by ready usable tins. Due to this development, many natural products got discontinued. Many traditional craftsmen and artists ran into difficulties procuring the needed materials,” says Kremer. “I studied chemistry, which is a good start for understanding properties when ‘cooking’ and mixing raw materials, and I was interested in serving this niche market.”
It wasn’t long before luthiers started knocking on his door.
“Violin makers are very curious—some did find out about my new company right in the first year, 1977,” says Kremer. Believing that authentically recapturing the past couldn’t be achieved with modern chemicals, he began to investigate varnish formulas from this perspective.
“In the medieval times, there had been mostly materials from natural sources. The exudations of trees and seeds became resins and oils. We supply the real natural materials; if used appropriately, the artist gets the same quality of layer as 500 years ago,” says Kremer. “The most famous artists did have secrets, which to copy is sometimes difficult.”
Which brings us back to Stradivari. Since the last years of the 18th century, both luthiers and the general public have been fascinated with finding the exact recipe the storied violin maker used. At the very end of the 19th century, the great violin impresarios the Hill brothers of London asked Giacomo Stradivari (1822–1901) about the varnish recipes of his great-grandfather in their 1902 book Antonio Stradivari, his life and work (1644–1737). Though he recounted the dramatic story of finding Antonio’s bible from 1704 with a varnish formula hidden in it, he would not share it with them.
“You make an impossible request, one which I cannot grant you, as I have never confided the secret of the varnish even to my wife or my daughters,” wrote Stradivari. ”You may consider it an eccentricity on my part, but nevertheless, until I arrive at a different opinion, I wish to be consistent with and remain faithful to the resolution of my youth never to reveal to anybody the contents of this precious recipe, holding steadfastly to the conclusions I arrived at when still a boy: that, if by chance other Stradivaris—my sons, nephews, grandsons, or grandnephews—should turn their attention to mechanics, more especially to the craft of our celebrated ancestor, they should then at least have the advantage of possessing the recipe of his varnish, the possession of which could not but be of material assistance to them.”
Speculation over the centuries has been rampant as to what Stradivari did to his instruments to make them sound both powerful and yet silky. The technology available at the time of the Popular Science article wasn’t up to the task, as they wrote, “every conceivable test has been applied to the varnish of genuine Strads, in the effort to analyze it and reproduce it, but without success.” It was left to modern science to search for the recipe as new methods were used to investigate for the possibility of a pulverized volcanic rock or some other mineral in the varnish that might have some special effect.
In 2009, Jean-Philippe Échard, a chemist at the Musée de la Musique in Paris, found the answer was not that exciting. “It’s a very basic recipe,” said Échard to the New York Times, after publishing a paper in a German chemistry journal, Angewandte Chemie International Edition. A first coat of linseed or walnut oil, followed by a coat of oil and tree resin with pigments added turned out to be the answer to the great secret—nothing particularly earth shattering. “The ingredients were simple, so probably the skill was in his hand and eye,” Échard said. Though addled by inferior tech, Popular Science came to this same conclusion 80 years earlier when they wrote that “the method of applying it has as much to do with its tone-producing quality is probable.”
But, as any cook knows, even a straightforward dish only flourishes with the use of great ingredients. “Our research surrounding old recipes of traditional paint making brings back to light many long-forgotten materials. In addition, we experiment with many different natural materials such as stones, bones, or roots, which allows us to create new, until now unknown, shades and variations of hues,” says Kremer. Violin Varnish of 1710, a mixture of shellac, sandarac, and amber that was made using an old German recipe, is an example of this process.
Although the precise reason Stradivari’s violins sound as they do has yet to be settled, no one doubts that varnishing an instrument does affect it. “A violin’s ground coat and the varnish have an impact on the elastic modulus of the wood as well on the impedance of the transmission of sound. The hardness and elasticity of the different coats influence the development and relative intensity of harmonic overtones,” says Kremer. The ground coat, which in effect seals the wood from absorbing too much of the oil in the varnish, is followed by layers of varnish. Kremer offers both oil-based varnishes and spirit varnish, wherein the resins are suspended in alcohol.
It is the differences and the details that Kremer has come to value most in his 45 years in business. “The development of the personal understanding about spirit and oil varnish is crucial for every violin maker,” says Kremer. “Violin makers are not so many, and they are very individual… I take the opinion of every customer seriously.”