Grinding coffee is the act of breaking roasted coffee beans down into smaller chunks which allow the compounds in the coffee to be easily dissolved or suspended in water, resulting in a coffee. There are two main categories of coffee grinds, as dictated by the coarseness or fineness of the grind; espresso or filter. Espresso grind is extremely fine and designed to be compressed into a 'puck' of ground coffee to pass water through at pressure, filter grinds can vary from the consistency of table salt up to coarse sand.
Due to the high pressure nature of espresso extraction, an espresso grind is much harder to get right than a filter grind. It needs to have a highly consistent grind size and care needs to be taken that the burrs or burr housing does not get over-heated and cause the aromatic compounds to breakdown or sublimate from the coffee. As such, a better grinder is normally required when grinding for espresso. Qualities to look for in a good espresso grinder are: low RPM (revolutions per minute), an ability to make fine adjustments to the grind, a high quality burr set and a built in timer to control the weight of the grinds.
For filter, the requirements are less strict due to the more relaxed nature of the brewing process. However, it is still important that the quality of the grind is of a consistently high quality. You should always ensure you are using a coffee grinder with two burrs rather than a grinder with spinning blades for both espresso and filter.
Burr versus Blade
Burr grinders are considered better because they create a consistent grind fineness. Inconsistencies in grind fineness occur with a blade grinder. If your grind is inconsistent the smaller grinds will brew faster than the larger grinds resulting in a poor extraction. Also, blade grinders can take a lot longer to grind the same quantity of coffee as a burr grinder, resulting in a build up of heat which can break down the aromatic compounds within the coffee.
When choosing a grinder, always consider which grinder would be an ideal choice for your brew method.
If you're brewing filter, a manual Hario Slim or the electric Baratza Encore grinders are ideally suited.
If you're creating espresso, we recommend the Vario Home for its versatility, high quality burr-set and innovative grind adjustment system.