THE PROCESS IN MOTION

Why does the percolator overextract?

Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.

▶ Play the process01The water boils, the steam lifts it02It falls back onto the basket03The cycle starts again04Two defects that add up05The drip coffee maker: a single pass

The water boils, the steam lifts it

In the pump percolator, the water boils at the bottom of the pot, and the steam lifts it through a central tube. The appliance is first French: Laurens (1819), Gaudet, Gandais and Durant filed its successive forms.

Read the stages without animation

1. The water boils, the steam lifts itIn the pump percolator, the water boils at the bottom of the pot, and the steam lifts it through a central tube. The appliance is first French: Laurens (1819), Gaudet, Gandais and Durant filed its successive forms.
2. It falls back onto the basketThe water falls back at the top onto a basket of grounds, passes through it and descends again into the pot. The process sits halfway between decoction and steeping.
3. The cycle starts againThen the cycle starts again, until the desired shade. It is not a percolation, says Ukers: the water does not cross the bed once and flow out, it is coffee already steeped that passes back over the grounds.
4. Two defects that add upThe grounds receive hotter water than in any other method, since it comes straight from boiling, and it is coffee, not clean water, that passes through them. Both push toward overextraction: the Mellon Institute measured 2.90 grains of “tannin” per cup, against 0.29 for filtration.
5. The drip coffee maker: a single passThe electric drip coffee maker passes the water through only once. The Moccamaster heats to 100 °C in a copper element and reaches the grounds between 92 and 96 °C. The SCA requires 92 °C within the first minute, never more than 96 °C, 4 to 8 minutes of contact.

To remember: The percolator runs boiling coffee back over the coffee: that is the very recipe for overextraction, which the drip coffee maker replaced with a single pass.

In history: It took until the early 1970s and electric drip coffee makers for it to be supplanted.

Read the full article and its sources ↓

The pump percolator is not a true percolation, says Ukers, and the name is misleading. The water does not cross the bed once and flow out. It boils at the bottom, the steam lifts it through a central tube, and it falls back onto a basket of grounds. Then the cycle starts again, until the desired shade. The process thus sits halfway between decoction and steeping.

The appliance is first French: Laurens (1819), Gaudet (1820), Gandais (1827) and Durant (1827) filed its successive forms. By 1825, it is widely used in France, Holland, Germany and Austria. Hanson Goodrich, of McLeansboro (Illinois), patents on August 13, 1889 (US 408 707) the American form, the one placed on the stove. General Electric publishes in 1905 Coffee Making by Electricity, and automatic models follow in the 1940s.

The defect is not a matter of taste, it is physical, and it is double. The grounds receive hotter water than in any other method, since it comes straight from boiling. And it is coffee already steeped that passes back over the grounds, instead of clean water. Both push in the same direction, that of overextraction.

The verdict is old. As early as 1915, Aborn, rapporteur of the American roasters' committee, condemned it as “a very defective utensil.” The analysis of the roasters' association, presented in 1913, quantified the gap: 2.90 grains of “tannin” per cup for the percolator, against 0.29 for filtration on pulverized grounds.

It would still take until the early 1970s, and electric drip coffee makers, for it to be supplanted.

Ukers 1922, ch. XXXIV and ch. XXXVI (Aborn report 1915, tannin table); Wikipedia, Coffee percolator (Sept. 7, 2026)

The electric drip coffee maker is German. Gottlob Widmann's Wigomat, patented in 1954, held water at 94-95 °C, and that range became the standard of the genre. Douwe Egberts distributed it in the Benelux and in France.

Gerard-Clement Smit's Moccamaster (Technivorm, Amerongen) was designed in 1968 and has been sold since 1969. Its principle is to heat higher than the target. The water rises to 100 °C in a copper element, and arrives on the grounds at between 92 and 96 °C: the journey costs it those few degrees. Ten million units in 2017, 137 parts, manufacture still Dutch.

In the United States, Vincent Marotta and Samuel Glazer launch Mr. Coffee in 1972. The scheme is simple: water passes over a heating element, is sprayed onto a paper filter, and the carafe is kept warm on a plate. The appliance replaces the percolator in American kitchens.

The SCA ended up controlling the machines themselves, and not only the cup. Its Certified Home Brewer program sets measurable requirements. The water must reach 92 °C within the first minute in contact with the grounds, then stay there without exceeding 96 °C. Contact lasts 4 to 8 minutes. And the cup must fall within the 18-22% window.

The 2023-2026 list has fifteen models:

• OXO, GE Profile and Café, Braun, Mr. Coffee Perfect Brew
• Zwilling and Fellow Aiden in 2024, then Krups, Aarke
• Breville and Cosori in 2025-2026.

Wikipedia (de), Wigomat; Wikipedia, Technivorm; Wikipedia, Mr. Coffee; SCA, Certified Home Brewer Program Requirements (2017) and sca.coffee/certified-home-brewer (accessed Sept. 7, 2026)