Coffee and Espresso Machines Espresso machines use pressure to press water into finely crushed and tamped beans. They produce a rich, delicious cup. Good Housekeeping Institute experts recommend models that use a minimum of 9 bars for a perfect extraction. Beware of brands that advertise more pressure than is needed. https://coffeee-uk76929.blogdon.net/all-inclusive-guide-to-coffee-machines-espresso-45959705