The instructions that follow are meant to elaborate and complement those provided by the manufacturer of your espresso brewer. Be certain you have read and understood the safeguards, cautions, and instructions that accompany your brewing device before supplementing them with the advice and encouragement given below.
There are two requirements for making good espresso. First, you must grind the coffee just fine enough, and tamp it down in the filter basket just firmly and uniformly enough, so that the barrier of ground coffee resists the pressure of the hot water sufficiently to produce a slow dribble of dark, rich liquid. Second, you need to stop the dribble at just the right moment, before the oils in the coffee are exhausted and the dark, rich dribble turns into a tasteless brown torrent.
Timing is everything in espresso brewing. The richest and most flavorful coffee issues out at the very beginning. As brewing continues, the coffee becomes progressively thinner and more bitter. Consequently, collect only as much coffee as you will actually serve. If you are brewing one serving, cut off the flow of coffee after one serving has dribbled out, even if you have two servings’ worth of ground coffee in the filter basket. If you are brewing two servings, cut off the flow after two. And no matter how many servings you are trying to make, never allow the coffee to bubble and gush into your serving carafe or cup. Such thin, over-extracted coffee will taste so bad that it’s better to start over than to insult your palate or guests by serving it.
If you are using a pump or piston machine, each shot or serving of espresso should dribble out in about 15 to 20 seconds from the moment the first drop appears. However, gauge when to cut off the flow of coffee by sight, not by clock or timer. The fineness of the grind may vary, as will the pressure you apply when tamping. Consequently, the speed with which the hot water dribbles through the coffee will also vary from serving to serving. If in doubt, cut off the flow of coffee sooner rather than later. Better to experience a perfectly-flavored small drink than an obnoxiously bitter large one. As you gauge the flow of coffee keep in mind that it will continue to run into the cup or receptacle for a moment or two after you have turned off the pump or shut off the coffee valve.
If you use a pump or piston machine, brewing into a jigger, or bartender’s shot glass, is a simple way of making certain that you do not produce overlong, bitter-tasting shots when you are brewing for frothed milk drinks. For a classic 1 1/4-ounce serving, brew the shot, including crema, up to the line on the glass.
If your brewer does not have a mechanism for cutting off the flow of the coffee, you will need to improvise. If the design of the machine permits, use two separate coffee-collecting receptacles, one to catch the first rich dribbles, which you will drink, and a second to catch the pale remainder, which you will throw away. Whatever you do, don’t spoil the first bloom of coffee by mixing it with the pale, bitter dregs.