The principle of a vacuum brewer was to heat water in a lower vessel until expansion forced the contents through a narrow tube into an upper vessel containing ground coffee. When the lower vessel was empty and sufficient brewing time had elapsed, the heat was removed and the resulting vacuum would draw the brewed coffee back through a strainer into the lower chamber, from which it could be decanted. The Bauhaus interpretation of this device can be seen in Gerhard Marcks' Sintrax coffee maker of 1925.
The gist: Okay, so in case any connoisseurs out there have been reading this section and thinking "a portable espresso machine takes the art away from espresso-making," this one's for you. Flair claims that this model was the answer to their question "What is the minimum needed to brew a professional-level shot of espresso?" The resulting product is this single-lever machine that doesn't need pods or electricity. It pulls a quality shot at 8-16 bars of pressure, has a 60ml water capacity, and brews a single cup in 25-45 seconds. You can get it in either black or chrome colors.
A refinement of the piston machine is the pump-driven machine, which was introduced in the Faema E61 in 1961, and has become the most popular design in commercial espresso bars. Instead of using manual force, a motor-driven pump provides the force necessary for espresso brewing. Espresso machines are made to accept water directly from a cold water line supply, common in commercial installations, or from a separate tank that must be filled with water by hand. The latter is more common with lower-volume commercial installations and domestic espresso machines. Due to the required high pumping pressure and precision flow control needed, the particular type of electric pumps typically used are known as solenoid-piston pumps. These pumps are classified as a positive displacement type (general category) of pump.
The machine is super easy to use: just choose either a single or double shot, select your coffee grounds, fill the milk and water reservoir and choose your brew. The water reservoir is removable, allowing for easy fill-up in the sink. The Café Barista also boasts the fastest preparation time when compared to other Mr. Coffee espresso makers. And at less than $200, this model is WAY less expensive than some of its competitors, giving you a great bang for your buck.
Hand-tooled and bench-tested in Italy, this espresso maker looks, works, and performs like it belongs in a small coffee shop, despite fitting tidily on your kitchen counter. This machine is built to last 10 to 15 years; less expensive machines at best might survive the five-year mark, and some can’t be expected to reach three. We also loved the sheer quality of every part included with our Rocket. The heft metal tamp fits perfectly in the machine’s own portafilter baskets and improved the shot-making experience of other machines when we used it with theirs.