CoffeeVacuum Coffee - Say What?
Invented by Loeff of Berlin in 1830s vacuum method of brewing coffee fell out of favour by the 1960s but started to make a comeback in the 1990s and is growing more popular in 21st century. There many different names for these "machines" - vac pots, vacuum brewed coffee, siphon brewer, siphon vacuum coffee, syphon coffee maker etc.
If you have ever seen any of these coffee makers, your first question probably was - how on earth does this thing work?
A siphon brewer basically contains 4 parts - a bottom container, where you pour water; a top container, where you put coffee grounds; a siphon tube that connects the containers; and a filter, where the liquid and gases pass through. The devices working principle is based on expansion and contraction of a gas (water vapor). The bottom container is heated up, which creates the water vapor that pushes the water up the tube and through the filter to the top container. Once most of the water has moved to the upper chamber the gas can escape through the siphon tube (the tube doesnt touch the bottom of the lower chamber, theres a little gap between them). Escaping vapor keeps the water in the upper container at the necessary temperature (it may look like its boiling, but its actually not). The process continues for 1 to 3 minutes, then you remove the heat source. That basically creates the reverse reaction, where the vapor in lower chamber cools down and contracts (some of it converts back to water), creating vacuum and therefore the suction that pulls the liquid from the upper chamber down to the bottom container. The effect is so strong that the coffee grounds are practically sucked dry in the process.
Originally the vac pots used simple wick burner to heat up the water and some still do. Nowadays there is a bit more variety of heating sources available. In principle they pretty much fall into two categories - the stovetop (gas or electric) use and self-contained heating devices like alcohol wick burners and butune burners. Of all these sources, wick burners are the slowest and butune burners the fastest. If you want to go for the latter option, look for the burners that have easily controllable flame - its essential for the great siphon coffee.
Siphon coffee makers come in many different sizes, most common ones being 12 ounces (3 cups), 20 ounces (5 cups) and 32 ounces (8 cups), but there are also brewers for as little as 4 ounces and as much as 48 ounces.
There are different types of siphon brewers available, most common being two globe type (the one in the picture). Here one vessel is sitting on top of another and siphon tube is in between them. Another more common type is a balance brewer, which works in the same principal, however the liquid moves side to side instead of up and down.
When vac pots fell out of favour, only handful of manufacturers kept producing them. With the recent rising popularity of these coffee makers more companies are considering in bringing them back to production. In Japan vacuum coffee is even more popular than drip coffee, which is probably also the reason why many siphon coffee makers are produced by asian companies including Tayli, Hario and Yama. A well known vac pot manufacturing company in Europe is Bodum with its coffeemaker called Santos.
Siphon coffee makers might take some trial and error to get used to it, but they are interesting and entertaining way to make coffee (and they make good coffee, I must say). Let"s face it, there are not that many coffee makers that look as if they were lifted right out of science lab.