Grinding Coffee for a Great Cup
My grandmother used to get up at 4 am, take down a five pound can of Hills Brothers ground coffee and start the percolator. She didn’t worry about grind size because the can told her this was the perfect grind for percolators. It must have been the right grind because the coffee kept my grandfather going all day long.
Visitors to the Hula Daddy Kona Coffee farm often ask us what grind to use for their coffee. We tell them that the size of the coffee grounds depends on two things; (1) the coffee filter they are using and (2) the brew method.
Brewing coffee is all about extraction – getting the good flavors out of the bean and into the cup. One of the key factors is the amount of surface area that is exposed to the brew water. The finer the grind the more surface area of coffee that is available. This might suggest that you should grind coffee beans into powder to get the most extraction. However, there are good flavors and bad flavors in coffee beans. For example, Turkish coffee uses an extremely fine grind, however, it is bitter and needs to have sugar to be drinkable.
Extraction is a continuum from thin/sour to acidic/bitter. When hot water is poured over ground coffee the first flavors are sour, as the extraction continues the flavors become bright and sweet. Finally, when coffee is over extracted the flavors become acidic and bitter. The best coffee flavors are In the middle of the continuum. So the goal is to extract the good flavors while avoiding the bad flavors. One element in achieving that goal is the correct grind size.
Using a grinder that produces even grounds is critical. If the grinder produces some large, some medium and some fine chunks, the large grounds are going to under extract and the small grounds are going to over extract. Over and under extraction do not cancel each other out.
Look at the grounds before you add water. Make sure they are all about the same size. If not, you need a better grinder.
Type of Filter
The right grind size is limited by the type of filter you are using. There are metal, gold plated, plastic, cloth and paper filters. Each one has a different porosity.
One of life’s major frustrations is pouring brew water into a filter basket and not seeing anything come through. It happens to everyone. Obviously, the coffee was ground too fine and it jammed the filter.
You can experiment with the filter you are using by grinding finer and finer until the filter starts to jam.
The shorter the brew time the more surface area you need for extraction. An AeroPress which has a short extraction time needs finely ground coffee. A French press which has a four minute extraction time needs a medium-coarse grind.
Coarse ground coffee works well for Cold Brew, Cowboy Coffee and French Press coffees. Coarse ground coffee is about the same size as kosher or sea salt.
Medium-coarse grinds work well for Clever, Café Solo and Chemex brewers. Medium-coarse grinds are smaller than kosher salt but larger than table salt.
Medium ground coffees work well for automatic drip coffee makers, Medium ground coffee is about the same size as table salt.
Medium Fine Ground
Medium fine ground coffee works well in siphon coffee makers. Medium fine grinds are smaller than table salt but larger than fine sand.
Fine ground coffees are needed for manual pour over, Aero Press, espresso and moka pots. Fine coffee grounds are about the same size as fine sand.
Extra Fine Ground
Extra fine ground coffee is used for Ibex brewers (Turkish coffee), and is about the consistency of powdered sugar.