The initial stage in all “pour over“ filter extraction processes, during which the ground coffee from which the drink is to be extracted is covered with a quantity of water equal to approximately double its weight.

This allows for pre-infusion (around 30 seconds) during which time the ground coffee is heated, causing it to release CO2 (degassing stage), and is prepared for the extraction stage.

Bubbles form on the surface of the coffee during degassing stage, hence the name “blooming”.