Espresso

Espresso is the only common method where a one-notch grind change ruins the result. Everything about an espresso setup (the grinder, the basket, the distribution tool) exists to keep that variable under control.

The three numbers

Dose in, liquid out, time. Eighteen grams in, thirty-six out, twenty-five to thirty seconds is the reference point, not a law. Change one and the other two move: that relationship is the whole craft. Weigh the shot, because volume lies as soon as the crema is different.

Why the grinder outranks the machine

At nine bars the water takes the easiest path through the puck, and the grinder decides whether there is an easy path. A cheap grinder makes a wide spread of particle sizes, the fines block, the water channels, and no machine fixes it. A good grinder on a modest machine beats the reverse every time.

Reading the shot

• Fast, pale, sour: too coarse, or the dose is low. Grind finer.
• Slow, dark, bitter and thin: too fine. The puck is choking and the water is stripping whatever it can reach.
• A jet from one point in the basket: channelling. That is preparation, not grind: distribute, then tamp level.
• Blonding early: the good part of the extraction is already over. Stop the shot rather than fill the cup.

Dialling in takes a bag, not a shot

A new coffee needs three or four shots before the numbers settle, and a bag needs re-dialling as it degasses over its first week. That is normal, and it is why espresso rewards buying the same coffee twice.