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David Gusset Studio
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1611 Lincoln Street
Eugene, Oregon, USA
Hours by appointment
violin, cello, viola, David Gusset, David Gussett, violoncello, stringed instruments,Stradivari, Stradivarius, Cremona, Guarneri, Guarnerius, instrument maker, history, Italian, Amati,AFVBM, violin varnish, design, luthier, making
Those who have had little or no first hand experience in the fine art of violin making or in personally handling great instruments, have attributed the renown of Stradivari and the early Italian instruments solely to the magical properties of some "lost" or "secret varnish recipe". That conjecture entirely discounts the artistry and numerous skills of the maker and all the many other aspects requisite to the crafting of a fine violin. It is like saying that if it were not for the color and consistency of their paints, Leonardo or Michelangelo could never have achieved greatness.
As soon as the instrument is completed "in the white" (all wood carving and gluing completed), it must be exposed to the air and sun for a period of several days to weeks to take away the whiteness of the freshly revealed wood. Air darkens the wood by oxidation. Ultraviolet rays of the sun (I often use artificial UV lights) suntan the wood. As the wood darkens, its visual depth and figure become more pronounced.
The next step, before varnishing, is the application of the "ground" coating, done in much the same way as painters of old prepared their panels and canvases for painting. The ground coat not only enhances the wood's beauty by further accentuating its depth and transparency, but also penetrates and strengthens the wood. When the overlaying varnish has worn or chipped away with age, the ground coat continues to provide protection from perspiration, moisture, dirt and other deleterious factors. This coating (probably more than the varnish itself) has proved to be the most elusive element of the so called "great mysteries" or "secrets of Stradivari" which has sparked controversy among violin makers for over 200 years. Recent electron microscopy of the varnish layers of historic instruments has revealed a thick layer of mineral ground.
Scientists, Dr. C.Y. Barlow and Dr. J. Woodhouse of Cambridge University, England were recently able to investigate the varnish and ground layers of a number of historic instruments. Their work was carried out on fragments of authentic instruments made by Stradivari and others. Using the SEM (Scanning Electron Microscope) they discovered a distinct particulate ground layer sandwiched in between the varnish layer and the wood on certain instruments. Using EDAX spectrum (Energy Dispersive Analysis by X-Rays) on selected areas of the samples that were positioned under the SEM, Drs. Barlow and Woodhouse were able to further analyze the composition of the ground layer. They determined that the ground layer on many of the early instruments was largely composed of a mineral rich mixture, high in silica and alumina.
Scanning Electron Microscope photographs (courtesy of Drs. Barlow and Woodhouse) of samples taken from three historic instruments. In all the examples, one sees three distinct layers: a layer of varnish, on top of a generally thicker mineral rich particulate layer, on top of a fragment of the wood. (Click on photograph for more detailed view)
Sample taken from a cello made by Pieter Rombouts (a contemporary of Stradivari who worked in Amsterdam). The scale bar in the upper left corner of the photograph gives the length scale. It corresponds to 30 micro-millimeters or 0.03 mm. The curving line at the top center is a crack in the surface of the varnish. The ground layer (particulate layer) can be seen to be several times thicker than the actual varnish layer
Sample taken from a bass by Matteo Goffriller of Venice, c. 1720. A very clear distinction can be seen between the varnish layer (smooth region) and the ground layer (underlying region showing particulate matter). The cylindrical object sticking out from beneath the chip appears to be a brush hair. (Click on photograph for more detailed view)
Sample from an instrument by Antonio Stradivari (Click photo for detailed view)
Violin varnish is applied with a brush in two or more coats. It is composed of sun-thickened oils such as linseed or walnut, oxidized resins and added coloring matter. Good historic Italian varnish is highly translucent and soft, yet friable. The surface has texture and a delicate patina, not a new car gloss. The colors should be warm and rich. Another characteristic of good varnish is dichroism (showing two colors); i.e., a thin layer will be golden and a thicker layer, reddish.
For additional color, lakes are ground fine and stirred into the liquid varnish or applied as a glaze between coats of varnish. Lakes are organic pigments made by precipitating natural dyestuffs usually onto alum. Three common lakes are "robbia" made from madder root, "verzino" made from brazilwood shavings and "carmina" made from cochineal. Grinding is done with a glass muller over a sheet of roughened glass. The microscopic colored crystal lake particles remain isolated and suspended within the varnish layer allowing light to freely penetrate between the crystals, maintaining the translucency of the varnish. Yet, as light passes through the varnish layer on its course to and from the wood, it is refracted in multiple directions by the colored crystals, lighting up the varnish as if it were one homogenous color.
Much of what intrigues the eye about varnishes on old instruments is the contrast in colors, transparencies and textures resulting from aging, chipping and wear. Areas which retain varnish look brilliant and fiery. In adjacent areas where the varnish has completely chipped away, the exposed ground layer appears dull, pearly or milky. A greater illusion of depth to the varnish is created over time by dark oxidation, dirt, rosin and polish accumulating just inside the broken edges of chipped away varnish and in the crackle or tiny fissures of the aging varnish layer. Artificially recreating this process on a new violin is a common technique for "antiquing" or making copies. To my eye, there are very few makers who do antiquing well. Although I occasionally make antiqued copies of old instruments, I prefer to make the same models like new, with all their crisp sculptural details and full varnish, and let the instruments age naturally.