There’s a million ways to pull a bad shot of espresso, but the easiest way is to mess up the tamp. Although it might appear to be a menial task, tamping is essential for an even extraction, i.e. ensuring all of the coffee grounds are saturated with the same amount of water. Any inconsistencies in the bed of coffee grounds and the water will channel, resulting in an unpleasant, astringent espresso.
As a barista educator, I can testify there are few bar skills that take as long to master as tamping. Even veteran baristas tend to tamp at a slight angle, ensuring the full flavor potential of that shot of espresso goes unrealized. Traditional tampers have the further problem of placing a lot of tension on the barista’s wrist. More than one barista I know has needed physical therapy because of repetitive stressed caused by tamping. The UK’s Clockwork Espresso claims to address both of these issues with a revolutionarily simple device they call the PUSH Tamper….