Espresso coffee blends are very finely ground to facilitate the extraction speed typical to this method of preparation, thus allowing the water to capture the maximum amount of aroma in a few seconds.
The correct grade of grinding for an espresso is achieved when 25 ml of coffee is obtained in 25 seconds using 7 g of ground coffee with a steam pressure set at 9 bar.
A medium grind blend is the most suitable for the moka pot, while American coffee, prepared with the filter coffee maker known as a plunger or French press, requires a coarser grind, able to soak up the water for the time it takes to brew and to transfer aroma.