In my time as a violin enthusiast, I have frequently come across instruments made in the second half of the 18th century in Austria, Bohemia, Germany and even in France, that have varnish either of an extremely dark hue, or completely black. When looking into the available literature on the matter I found the explanations of luthiers and experts always left me perplexed, and none seemed satisfactory. The explanation most commonly given is that, over a short period in that century, violin makers in the German-speaking countries failed to maintain consistency in their varnish making: in their enthusiasm for experimentation and new effects, they made mistakes in the mixture. Sometimes they added too much resin to the varnish recipe; or sometimes there would be too much silver or iron nitrate, thus making the instruments darken with time, even becoming black due to oxidation. Hence, according to these explanations, the dark varnishes were down to errors in the recipe, more because of the chemical proportions than to the incompetence of the violin maker as such.
But how could what might be called a collective memory lapse be explained? There had to be another reason; hundreds of violin makers, sometimes working more than 1,000 miles apart, could not all start to make similar mistakes in their varnish formulas, all at the same time. Also, I never heard it argued that the dark varnish might have been a deliberate choice of the violin maker.
Passing through Vienna one day, I stopped at the Belvedere Museum to admire the magnificent paintings of Gustav Klimt. As I was strolling through the lobby, in front of the reception desk I saw an enormous notice of mourning on the wall in front of me. This document, impressive because of its size, was a decree by the Empress Maria Theresa of Austria which fixed the conditions and the rules for mourning to which both she and the Court of the Empire were subject, following the death of her husband Francis Stephen of Lorraine, Holy Roman Emperor, who had died on 18 August 1765.
Later, I was perusing the biography of violin maker Pietro Mantegazza of Milan in the Universal Dictionary of Violin Makers by René Vannes. In combination with the above notice, I was convinced I was on the right track to explain the reason for the black and dark instruments. Vannes states:
In a time of mourning in the entourage of the Empress of Germany, Maria Theresa (1717–80), Mantegazza had to apply black varnish to the quartet of instruments that she had ordered.
At that time, the duchy of Milan was an integral part of the Austro–Hungarian Empire. For me, this was the first proof that there was a link between the mourning period of Francis Stephen and the colour of the varnish of certain instruments.