You dialed the grinder in yesterday. Same beans, same dose, same machine. Today the shot runs fast, spurts from one side of the bottomless portafilter, and tastes sour and bitter in the same sip. That's channeling, and it's the most common reason good coffee turns into a bad espresso. Espresso works by forcing hot water through a bed of fine coffee at around nine bar. Water is … [Read more...] about Espresso Channeling Explained, Why Water Finds the Weak Spot in Your Puck and How to Stop It