The vacuum coffee pot, also now known as the syphon brewer, is a very old and exceedingly entertaining way to make coffee. It is, however, also extremely annoying in many respects and sufficiently frustrating that many people relegate their brewer to a cupboard or a shelf as a display piece.
Vacuum coffee pots first appeared in Germany in the 1830s. A patent was issued for one in 1838 to a French woman, Jeanne Richard. The design has not really changed a great deal since its conception. The brewer has two chambers, the lower of which is filled with water and heated to boiling point. The upper chamber, which contains the coffee grounds, is then placed on top, creating a seal and allowing steam to build up in the lower chamber. This trapped steam pushes the water from the bottom chamber up through a tube and a filter into the upper chamber. The water is, at this point, just below boiling point and suitable for making coffee. The brew is left to steep for the desired amount of time; it is important to keep heating the lower chamber while the coffee steeps.
To finish the brew, the vacuum pot is removed from the heat source. As the steam cools, it condenses back into water and creates a vacuum, which sucks the coffee from the upper chamber back through the filter into the bottom chamber. The grounds remain trapped and separate in the upper section and the coffee can be poured from the bottom carafe. The whole process is a pleasing application of physics, and is often likened to a classroom experiment. Unfortunately, it is sufficiently difficult to get right that most people try a couple of times and then give up, which is a shame.
Vacuum coffee pots are an elaborate way to make coffee by immersion. Steam rises from the lower chamber and steeps the coffee grounds held above, then condenses the brew into the lower carafe.
ADDITIONAL TOOLS
An independent heat source is required for this brewing method. Some vacuum coffee pots are designed to sit directly on a kitchen stove, others come with their own alcohol-burning candle. These candles are best replaced with a very small, butane camping stove. In Japan and in some specialist coffee shops, the preferred heat source is a halogen lamp placed under the brewer. This is not the most efficient source of heat but it does look fantastic.
Some people use small bamboo paddles to stir the coffee but these do nothing special and a spoon works equally well. While I cannot deny there is pleasure in acquiring and using a special set of tools for a ritual, I won’t claim they make any difference to the coffee.
THE FILTER
Most traditional vacuum pots use a cloth filter, which is wrapped around a metal disc. It is important to keep this cloth clean. After every use, clean the cloth as thoroughly as possible under a hot tap. If it is not going to be used for a few days, clean it with a suitable detergent. For more information about cleaning and storing cloth filters, see (Different Kinds of Filters). There are alternatives to cloth, such as paper or metal, but these often need special adapters.
THE VACUUM POT METHOD
Ratio: 75g/l. Some people prefer to use a little more coffee than this for syphon brewing, especially in Japan where this method is commonly used.
Grind: Medium/caster sugar. Because this is an immersion method, you can match your brew time to the grind size. I would caution against going too fine as you can stall the draw-down process to end the brewing. A very coarse grind will mean a very long brew time at higher temperatures, which can make the brew rather bitter (see Grind Size).
1 Grind the coffee just before you start brewing. Be sure to weigh the coffee first. 2 Boil a kettle of fresh water with a low mineral content, suitable for brewing coffee. 3 Fit the filter into the upper chamber, making sure it is completely flush. 4 Place the bottom chamber on your digital scales and pour in your calculated amount of hot water, following your desired ratio. 5 Transfer the lower chamber to your heat source (a small butane burner, an alcohol burner or a halogen lamp, as shown here) using the handle to move it. 6 Place the upper chamber on top, but do not seal it yet. If you put the seal on too soon, the expanding gases will push the water up into the top chamber before it is the right temperature, making your coffee taste bad. 7 When the water starts to boil, seal the top chamber on top of the lower chamber. If you are using a controllable heat source, reduce the heat to low at this point. The boiling water will now start pushing up into the top chamber. Look directly down on the filter to make sure it is centred: if it isn’t, you will see lots of bubbles flowing from one side. Use your paddle or a spoon to push the filter carefully into place so it is correctly positioned. 8 Initially the bubbling in the top chamber will be quite aggressive, with large bubbles. Once the bubbles become smaller, you are ready to brew. Add the coffee to the water and stir it in until it is all completely wet, then start a timer. A
9 A crust will form on top. After thirty seconds, give it a gentle stir to knock the floating coffee back into the brew. B
10 After another thirty seconds, turn off the heat source. Once the coffee begins to be drawn down into the lower chamber, stir it gently once clockwise and then once anticlockwise to prevent it sticking to the walls of the brewer, but if you stir too much you will get a large dome of coffee at the end of the brew, which suggests uneven extraction.
11 Allow the coffee to draw down completely. A slightly domed bed of grounds will be left in the top chamber. Pour the coffee into a coffee pot, as the retained heat from the carafe can give the coffee a cooked taste. C
12 Let the coffee cool. This brewing method produces an incredibly hot cup of coffee. D
Coffee was first discovered in ninth-century Ethiopia, and the Tomoca coffee shop in Addis Ababa is the oldest surviving café in the country. The later influence of Italian rule is seen in the sleek espresso machines.