The 1669 ‘Tullaye’ Stradivari violin (right) with its corresponding mould, the ‘S’
‘S’ MOULD COURTESY MUSEO DEL VIOLINO. ‘TULLAYE’ VIOLIN JAN RÖHRMANN
Similarly to how shoes are built on a last, violins in the Stradivari workshop were built on an internal mould. The ribs were bent around this mould, determining the dimensions of the corpus. The differences in size are not large, but they do affect sound and playability of the violins. We notice this as makers with our own violins, and, when studying Stradivari’s oeuvre it becomes clear that he consciously experimented with the proportions of his instruments.
Twelve of these moulds have survived, and are now housed at the Museo del Violino in Cremona. A lot of precious work has been done on the possible design of these moulds, most notably by François Denis. In 1994 mathematician David Woodrow published The Shape of Stradivari Forms and Violins, in which he analysed the changes in their dimensions over Stradivari’s 66-year career. Other valuable sources include Stewart Pollens’s 1992 book The Violin Forms of Antonio Stradivari and the chapter on the moulds in Simone Sacconi’s influential 1972 work I ‘Segreti’ di Stradivari, in which he gives his well-known interpretation of the letters inscribed on the moulds (‘P’ = prima, ‘S’ = seconda, ‘PG’ = prima grande, and so on).