Have you ever waited longer than you expected for an espresso despite being (seemingly, at least) the only customer at a cafe? Have you stood watching with vague horror as a barista pulled several shots in a row only to discard them? Have you ever wanted to grab said barista by the shoulders and shout, "What are you doing with all of this coffee, and where is my espresso?!" Don't worry—there's probably a method to the madness.
While hopefully a somewhat rare occurrence (not unlike trying to hail a taxi at the maddening "shift change" blackout time of 4 p.m.), the phenomenon you've experienced could likely be caused by a barista needing to "dial in".
Today, we'll look at what "dialing in" means, exactly—and maybe you'll actually be glad the next time you wind up waiting.
All coffee recipes and extraction techniques need to be tweaked in order for the finished brew to be just so, and "dialing in" can be used to describe any brewing method.
The parameters a barista might mess with while trying to perfect a cup include coffee-to-water ratio, grind size, brew time, and water temperature, among other things (depending on the brew method). For today, however, we'll focus on dialing in on the espresso machine.
For a novice barista, consistency in brewing espresso is the silver bullet in the arsenal of tools needed to improve quality, meaning that the person making the coffee needs to be able to re-create one good extraction after another. When inexperienced baristas make too many adjustments to technique or recipe ("What if I add less coffee?," or, "Maybe I shouldn't tamp as hard."), they tend to fall down the rabbit hole of bad-but-I-don't-know-why espresso, and can find themselves unable to make things right again.
Whenever I train newbies, I always tell them to focus on a single parameter at a time, starting with the size of the ground coffee particles. By controlling the coarseness or fineness of the grind, a beginner can either speed up or slow down the rate of the coffee's extraction, which allows him to make other decisions about what might be affecting the quality.
In order to "dial in" a coffee, then, a barista needs to know how long the espresso extraction should take (20 to 30 seconds for about two ounces of total output volume), and to understand that a coarser-ground coffee will brew faster than a finer-ground one, and adjust accordingly.
The more advanced barista might also amend her dose, or the amount of ground coffee she is using to make the espresso. She might also stop the flow of water through the espresso at slightly different times toward the end of the extraction, trying to find that sweet spot. Or she might take a moment to bump the brew temperature up or down a notch, if she's able.
In the end, a barista must taste his or her shots in order to know what's best, and though there's certainly the potential for overkill (i.e. you should never wait more than ten minutes for a freaking espresso—ever), as a general rule you can trust that the person making your coffee—and the five before it that he or she deemed unworthy of you—has only your best interests, and your taste buds, in mind.