The fascination of a lever extraction.
The lever system of the professional coffee machine allows the barista to set the pre-infusion time manually for every supply: when the lever is low, the hot water of the boiler enters the group, dampening the coffee cake. The more the barista keeps the lever low, the longer the pre-infusion phase will be. A skilled barista waits for the first drops of coffee the come out of the spout and then raises the lever; this means that the whole coffee cake is soaked.