I love the way this coffee company, Batdorf and Bronson
(great name!), compares the coffee grounds to salt, sand. Everyone knows the coarseness of these everyday things so it's a very accessible way to explain it to people who are just beginning in coffee.
They touch on some key points that help the beginner understand just how important the size of the grounds really is.
Grind was the topic of our Craft section in our very first magazine! It's that important, we couldn't think of a better lesson to learn than importance of grind! You can read it here.
"In general, we use a coarser grind for longer brewing times (filtered coffees) and a finer grind for shorter brewing times (espresso, aeropress). A coarse grind lets water pass through quickly. A fine grind slows the flow of water.
Thanks for reminding us Batdorf and Bronson!
One effective way to communicate and evaluate grind size is how it feels to the touch. Take a sample of ground coffee and rub it between the thumb and fingers. Coffee is ground into particle sizes ranging from something resembling kosher sea salt for coarse, sand for a medium grind, and powdered sugar for a fine grind.
Ultimately, it all comes down to taste. Taste is very subjective. Assuming all the other essential brewing variables are in line simply ask: Does the brew taste bitter, astringent, or too strong? Adjust the grind coarser next time. Does the brew taste weak, watery, flat or sour? Adjust the grind finer next time. Small adjustments make big differences. Keep the adjustments small at first then continue adjusting to find the sweet spot.
To put all of this information together in a way that applies to different brewing methods refer to the grind recommendation chart for a good starting point on your preferred brewing method. Now you should be able 'dial' in the grind and enjoy some seriously tasty coffee. Enjoy! "
Of course it is always important to note that with any guidelines, your preference should lead your way on your coffee path. Have fun!