Whoever first created the legend of Stradivari's mysterious varnish must have been a real marketing expert. After all, it is precisely this aura of mystery that has helped transform outstanding violins into collectors' items, commanding millions at auction.
Scientific research, however, paints a rather different picture. To this day, no analysis has discovered any mysterious or exotic ingredients. Instead, there is an agreement that Stradivari's varnish consisted primarily of two materials that were normally used at this time: linseed oil and rosin.
The real challenge, then as now, lies not in the ingredients but in their preparation. To produce a durable oil varnish, the rosin must be cooked at high temperatures for many hours—originally over an open fire. Because of the fire hazard, varnish making was strictly regulated or even prohibited within many towns. It is therefore quite possible that Stradivari did not cook his own varnish but purchased it from a specialist, perhaps modifying it slightly to suit his own requirements.
Today, anyone wishing to use a traditional Cremonese varnish will usually have to cook it themselves. Above all, the process requires patience.
Throughout the long cooking process, the rosin must be checked regularly until it reaches the desired degree of polymerisation. The exact ratio of rosin to linseed oil has never been documented, so there is no historical recipe to follow. In the end, there is only one way forward: experimentation.
For several years now, we have been regularly cooking our own traditional Cremonese varnish. Is the effort worthwhile? In terms of sound, I have not yet found any clear advantage. Visually, however, the results are remarkable. A traditional rosin varnish gives an instrument a golden depth and vitality that other varnishes rarely achieve.
And after all, we listen with our eyes as well.