If you're making puff pastry at home, Kirk recommends popping it in the fridge in between turns to give your butter a chance ...

This steam, trapped between the sheets, expands and "pushes ... So grab your rolling pin, chill the butter and get ready to get your puff pastry nice and crispy and puffy. 1.

Each time you do this, the butter chunks are flattened out into larger sheets and layered on top of each other. In proper puff pastry this is done in a regimented fashion, with end to end even layers.