At the beginning of the fermentation in the cuves we have whole bunches, since we keep all the stems. So at the start of the ferment we start by lightly crushing the grapes, as we crush the grapes, step by step we do 'pigeage'. We extract the juice, and as this ferments, the juice sinks to the bottom of the cuve. So by the process of fermentation and the release of CO2, the solid matter, meaning the stems, skins, and seeds, float to the top of the cuve. This 'cake' that forms at the top is what we call the 'cap'. So bit by bit as we do the 'pigeage', the cap forms, gets bigger and bigger, and thicker and thicker, and it's this cap which must be pushed down into the juice. Marina. Nearly 40!