Guides

Jargon Busters: Espresso Machines

Bar: The amount of pressure the pump in the espresso machine can create. Generally 8 to 10 bar must be used in the creation of espresso.

Boiler: Water is heated in the boiler before being pumped through the coffee. The boiler is an alternative to a thermoblock.

Bypass doser: Found on some automatic machines to allow two different types of coffee. The second coffee will generally have to be pre-ground.

Crema: When you've properly made an espresso, it will have a frothy aerated brown foam that floats on top of the liquid coffee. This is the crema.

Descaling: A process to remove mineral deposits from the inside of your machine. This needs to be carried out on a regular basis, more frequently if you use 'hard' water.

Filter: The filter fits into the portafilter. It's where the ground coffee is placed and contains small holes at the bottom that let liquid coffee — but not coffee grinds — through. Espresso machines usually come with two filters: one for a single cup and one for a double cup.

Group head: Where the portafilter attaches to the espresso machine.

Portafilter (or group handle): The portafilter holds the filter in which the ground coffee sits, and attaches to the group or brewing head. Once attached, the heated water can flow through the coffee under pressure.

Puck: The puck is the leftover used coffee in the filter. If the coffee is tamped properly, the puck should be dry and easy to get out of the filter.

Tamping: Once the coffee is in the filter it needs to be pressed down or tamped. The amount it needs to be pressed down will depend on how fine the coffee ground is and the design of the filter. If the coffee is not tamped enough the coffee will be watery and a crema will not develop. Tamped too tight and the machine will have difficulty pushing the water through.

Thermoblock: A large block of metal through which water passes to reach the required temperature for espresso or steaming milk. The thermoblock is an alternative to a boiler.

Water reservoir: Where the water is stored for the coffee machine before heating.