The development of espresso technology, which is also processed Graef's espresso machines, dates from the year 1901. 6 to 7 grams of fine coffee grounds had been extracted out of the machine in approximately 25 to 30 seconds and under high pressure (approx. 9 bar). During this process, the water has a temperature between 90 and 96°C. In case of Espresso Machines, the group handle manually gets filled with coffee grounds and then gets pressed into the filter basket of the group handle - a process which is called "Tamping".

The way of preparing coffee is differing among cultures, national habits or personal taste. For this, each bean gets, depending on the way of preparation, grounded in different coarsenesses. For most of the preparation methods, the utilized water has a temperature which is below the boiling point. In case the water temperature is too low, the coffee has a bland and sour taste. In case the water is too hot, more bitterns get dissolved from the coffee grounds and influence the taste.