Episode Details

The French press goes by many names: plunger in Australia, New Zealand, and South Africa, cafetière in the UK and Ireland, and Stempelkanne, or stamp pot, in Germany. A French metalsmith and a merchant, Jacques-Victor Delforge, patented a screen on a rod in 1852, but it had no seal, so pushing it down sent grounds up the sides into the coffee. The fix came from Milan in 1928 and 1929, when designers Attilio Calimani and Giulio Moneta wrapped the filter in a flexible coil spring that kept it flush against the glass.

A refined spring design patented in 1958 by Bondanini was produced by Martin SA, a French clarinet factory, under the Melior name, where precise metalwork for airtight instrument keys carried over to the plunger. Bodum and Household Articles Ltd spread it across Europe, and the 1965 Michael Caine spy film The Ipcress File made it look chic. The episode explains the immersion brewing chemistry, why a fine grind jams the plunger and over-extracts, and the press's second lives as a tea infuser and broth strainer.

• A standard brew uses about 30 grams of coarse coffee to 500 milliliters of water at 93 to 96 degrees Celsius, steeped around four minutes.
• The plunger stops about an inch above the bottom, so extraction continues until the coffee is poured off.
• Variants include hiking mugs with built-in plungers and a press with a heater that runs on 12 volt power.
• The American press seals the grounds in a mesh pod pushed through the water, and reverse designs lift the grounds into the lid.
• Coffee oils trapped in the spring and mesh will flavor tea unless every part is taken apart and scrubbed.