Carding department — Pavia-area hat factory

Italy's hat-making triangle — Alessandria with Borsalino, Monza, Voghera with the Berti family — produced tens of millions of hats a year in the early 20th century, in factories where the process lasted weeks and ran through more than forty distinct operations.

Rabbit and hare fur was 'secreted' with mercury nitrate to give it the cohesion of felt: chronic exposure caused the 'mad hatter's disease' — tremors, neuropathy, psychosis — already described in Pavia and Voghera from the early 1900s.

The use of mercury nitrate in felt was banned in Italy only in 1941 and the full switch took place after the war: for three generations of women hat-makers, the price of felt durability was paid in their health.

In the 1930s, women made up 80% of the workforce in the carding, blocking and finishing departments of Lombard and Piedmontese hat factories, but were systematically excluded from the higher-grade trades (secreting, fulling) reserved for men.