Espresso: the only brew with a target

Espresso is the one brewing method with an actual target rather than a range of preferences: a dose in, a weight out, and a time. Everything else — pressure profiles, basket brands, tamper weight — is refinement on top of getting those three right and repeatable.

Weigh the dose and weigh the yield. A scale under the cup is the single upgrade that improves more shots than any machine costing ten times as much, because volume lies: crema volume varies with roast date and tells you nothing about how much coffee is in the cup.

Water under nine bars of pressure will find any weakness in the puck and run through it, leaving most of the coffee barely touched. That is channelling, and it is why one shot tastes thin and bitter at the same time — you are drinking the over-extracted channel and the under-extracted rest together.

The fixes are all about the puck, not the machine. Distribute the grounds evenly before tamping, tamp level rather than hard, and avoid knocking the portafilter after tamping, which cracks the puck you just built.

Dose and yield stay fixed; you steer the shot with the grinder. Ran long? Grind coarser. Gushed in fifteen seconds? Finer. Change one thing at a time and pull again — chasing two variables at once makes the result unreadable.

Expect to adjust across a bag's life. Coffee degasses as it ages, and a setting that was perfect on day five will run fast by day twenty-five.

Espresso is the one method where very fresh coffee is a genuine problem. Carbon dioxide in a recently roasted bean disrupts the flow and gives a shot that gushes, tastes sharp and produces enormous pale crema. Most coffee is at its best for espresso somewhere between seven and thirty days off roast.

It also wants a grinder with flat or conical burrs and no other job. A blade grinder produces a mixture of dust and boulders, and dust plus nine bars is a blocked basket.