Let’s set the scene: It’s 7am on a cold wet day and your espresso machine has just reached brewing temperature. You’ve prepared everything you need for a full day of service, and have 5 minutes to spare before flipping the sign on the door to ‘open’. It’s just enough time to make your first coffee of the day, a delicious flat white.
You go to pull your first espresso shot of the day, but 20 seconds in and there’s still no sign of liquid espresso coming from the spouts of the portafilter. Your espresso is coming out far too slowly, leading to a thick and bitter shot of coffee that tastes awful compared to yesterday’s balanced, sweet and complex brew. You need to work out how to fix your slow espresso, as this is a problem you’re going to run into time and time again if you don’t know what to do. Continue reading this article or watch the two minute video below that explains how to make our espresso flow quicker by learning how to dial in your espresso grind size.
Why is My Espresso too Slow?
If your espresso is flowing too slowly, your coffee is probably ground too fine.
You’ve created too much surface area inside the coffee puck, and the water is struggling to get through leading to a slow and overextracted shot of espresso. So, to fix this, you’ll have to dial your coffee grinder a little coarser and let the water flow through the puck of coffee more easily.
Fixing a Slow Espresso with Grind Size
While you do this, you have to keep every other variable constant. So if you’re aiming for an 18 grams dose make sure you’re actually getting 18 grams, make sure you’re tamping and distributing your coffee evenly and consistently., and don’t change anything else like temperature, pressure or espresso ratio. Always change just one variable at a time.
How much coarser you go depends on how far you were from your target extraction time, after a bit of trial and error with your grinder you should start to get a feel for it and knowing how much of a difference to make will become second nature.
Every time you make a change, there’ll be a bit of the old grind size stuck inside the burr chamber. Make sure to purge and discard a dose of coffee grounds before testing the new grind size.
As you gradually grind coarser your espresso should start to come out faster. Don’t worry if you go too far and it flows too fast, just dial the grinder back a little finer and meet somewhere in the middle.
Why Do You Need to Calibrate a Coffee Grinder?
Even if your grinder was perfectly calibrated yesterday, there’s a huge number of variables that might be throwing off the extraction time including things out of your control like the temperature of the room, the freshness of the beans. That can make dialling in your espresso feel very frustrating, but knowing how to control things using grind size and going a little coarser if you need to will get you 95% of the way there.