“Legend has it that Amarone was born after a Recioto fermentation was left too long.
Before fermentation, the two styles have a lot in common.
(…) Key to the process is the appassimento method. This involves drying out harvested grapes, which concentrates sugars and fruit flavours. Grapes will lose weight as water content evaporates.
(…) These days, grapes are more commonly dried in lofts in a more controlled environment; inevitably, though, some have rejected the introduction of new technology in the process.
Grapes must be dried until at least 1 December following harvest, but it often takes longer and fermentation may not begin until January or February”.
It worths reading, here.