Dialing in

Change one thing at a time

Grind, ratio, temperature, time: four dials. Turn one per brew, or you’ll never know what worked; lock the rest up with the silver.

Use the map

When a cup is off, return to the extraction map from lesson 4 and move one dial. Sour means pull harder: finer, hotter, longer. Bitter means ease off. Weak but balanced: more coffee. Strong but muddy: less.

Cup to cure

Match each cup to the one change it wants.

• Sour and thin — Grind finer
• Bitter and drying — Grind coarser
• Weak but balanced — More coffee
• Strong and muddy — Less coffee

Sour and bitter are extraction, so the grinder answers them. Weak and muddy are strength, so the ratio does.

One dial, one direction

You grind finer and change nothing else. The marker moves…

Answer: Toward bitter: finer grounds give up more. That is the dial to reach for when a cup comes out sour and thin.

Clean gear, or none of this works

Coffee oils go rancid on every surface: the press screen, the AeroPress seal, the grinder’s chamber. Rinse after every brew; wash properly once a week. Stale oils lay a flat, musty note over everything, and no dialing in will shift it.

Rinse now, wash weekly

If coffee turns bad and nothing else changed, look here first.

How often does the gear want a proper wash?

Answer: Once a week. Rinse after every brew, wash properly once a week. No amount of dialing in will shift a musty note off rancid oils.

Fix this cup

Take this cup from sour to “That is the cup” in three brews.

You’re ready

You know what coffee is, how to brew it, taste it and fix it. One lesson left: for when you’re at the mercy of other people’s kitchens.