From the humble French press to multithousand-dollar home espresso machines, our java-fuelled society’s obsession with achieving the Platonic brew knows no bounds. Of late, even one of the oldest and oddest coffee makers has been experiencing a comeback. Pioneered in 1830s Europe, glass vacuum coffee makers saw their popularity spike in the early 20th century after the invention of heat-resistant glass. (Earlier versions tended to explode.) They fell out of favour with the advent of electric percolators, but, hearing that they could brew a perfect cup, I decided to test one of the more popular modern models: the Bodum Santos.
This contraption may generate flashbacks of Grade 10 chemistry class – though nerdy safety goggles are not required. The Bodum Santos consists of an orb-shaped funnel that sits atop a stubby eight-cup carafe. A long, slender tube housing a plastic filter extends off the bottom of the funnel into the carafe. Grounds are placed in the funnel and cold water in the carafe. A soft silicone collar creates an air-tight seal.
The device is simply heated on the stove and can be used on electric, ceramic or gas elements. I used ceramic, testing the coffee maker more than 20 times with a full-bodied, medium-ground French-roast bean. As the water heats, evaporation increases the air pressure in the carafe, pushing the water up the tube through the filter into the funnel, where the coffee is brewed. Removed from the heat, the device cools, creating a vacuum inside the carafe that sucks the brewed coffee down, leaving the grounds behind.
This is a fascinating process to watch, but I found that the manufacturer’s instructions to place the assembled coffee maker on the stove did not produce the best coffee. The trick was to wait until just before the water boiled before setting the funnel on the carafe. The optimal water temperature for extracting the best flavour from ground coffee is between 90.5 C (195 F) and 96.1 C (205 F). When the funnel is placed on the carafe too soon, there is enough pressure inside the carafe to force the water up the tube at much cooler temperatures. This results in a bitter, under-extracted brew.
Timed accurately, the coffee produced by the Bodum Santos was indeed the best I’ve ever made – complex, clean, vibrant and delicious, with just a touch of bitterness. Nature may abhor a vacuum, but when used right, coffee adores one.
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