Get the ratio right
Weak, sour coffee is usually a measuring problem. The standard starting point is one part coffee to sixteen parts water by weight, which works out to about 60 grams of coffee for a liter of water, or two level tablespoons for every six ounces. Note that the "cup" marked on most coffee makers is five or six ounces, not eight. Start there and adjust by taste.
Match the grind to the method
The longer the water sits with the coffee, the coarser the grind should be.
- A French press steeps for about four minutes and needs a coarse grind, like rough sea salt.
- An automatic drip machine wants a medium grind, like sand.
- A pour-over cone takes a medium-fine grind and about three minutes of pouring.
- Espresso and stovetop pots need a fine grind, close to powder.
A burr grinder crushes beans to an even size, and a basic hand-cranked model is inexpensive. Blade grinders chop beans into a mix of dust and boulders, which brews into a cup that is bitter and weak at once. If you own one, grind in short pulses and shake it between them.
Read the cup
Coffee that tastes sour, thin or salty is under-extracted. Grind finer, brew a little longer, or check that the water is hot enough, since the target is 195 to 205 degrees. Coffee that tastes harsh, bitter and drying is over-extracted, so grind coarser or shorten the brew. Change one thing at a time. If your tap water tastes of chlorine, the coffee will too, and a simple pitcher filter fixes it.
Buy and store beans
Look for a bag with a roast date rather than only a distant best-by date, and buy what you will drink in two or three weeks. Keep the beans in an airtight, opaque container in a cupboard. The refrigerator is a poor place for them, because beans absorb moisture and odors every time the container is opened.
Clean the equipment
Coffee oils turn rancid and cling to carafes, baskets and presses. Wash every removable part with soap after each use, not just a rinse. Minerals from the water build up inside automatic machines, so run a descaling cycle every one to three months, following the manual, and then run two tanks of plain water through.
Tip For cold brew, stir one part coarse-ground coffee into eight parts cold water, refrigerate it for twelve to eighteen hours, and strain. The concentrate keeps for about a week and is diluted to taste.
