The Melitta filter
A perforated filter holder, a sheet of porous paper, hot water poured over it: the coffee passes through the paper, the grounds stay inside. It is the most widespread motion in filter coffee, and its current form, the cone with a slotted bottom, dates from the Melitta patents of 1936 and 1937.
How does the paper filter separate the coffee from the grounds?
Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.
The folded sheet, seams turned over, sits on the ribs of the filter holder and goes down to the slot at the bottom. The paper is supported everywhere, so it no longer tears at the edge.
Read the stages without animation
- The paper in the coneThe folded sheet, seams turned over, sits on the ribs of the filter holder and goes down to the slot at the bottom. The paper is supported everywhere, so it no longer tears at the edge.
- Wetting the grindA first trickle of hot water, between 92 and 96 °C on contact, wets all the grind, which swells and releases its gas. The dry bed becomes a wet bed that the water passes through more evenly.
- The water passes through the bedClean water runs down through the grind and takes on dissolved matter. The water takes on color and becomes coffee.
- The paper sortsThe liquid passes through the pores of the paper; the grounds, some of the oils and almost all the diterpenes stay above. The cup is clear and nearly free of sediment.
- The slot sets the flowThe narrow opening holds a reserve of water in the cone, which drains in a few minutes. Contact time lengthens, four to six minutes, without any need to pour slowly.
To remember: The paper sorts, the slot sets the flow: a reserve of water waits in the cone and lengthens contact.
In history: In 1908 in Dresden, Melitta Bentz.
Read the full article and its sources ↓History
Paper is not an invention of 1908. Ukers points out, in 19th century France, a “made to order” coffee prepared in a funnel pierced with holes and lined with blotting paper or a woolen cloth, and a Parisian tinsmith, Casseneuve, who used a paper filter in his machine of 1824. In the United States, Cauchois sold a Japanese-paper apparatus in 1905, Acker patented the same year a percolator with a sheet of paper, and Richheimer's Tricolator followed in 1908 (source 6). Melitta's site nonetheless presents the 1908 filter as “the world's first paper coffee filter” (source 5): this priority does not stand up against the texts of 1922.
What is new in Dresden is the person and what followed. Melitta Bentz, a mother of three, pierced the bottom of a brass cup and placed in it a sheet of blotting paper taken from her son's school notebook. On June 20, 1908, she filed with the Imperial Patent Office in Berlin a utility model (Gebrauchsmuster), a lighter protection than a patent, for a “coffee filter with a domed underside, hollowed bottom and inclined drainage holes.” It was registered on July 8, 1908, and the company that sold these filters entered the commercial register on December 15 (source 1). The office's poster gives the number 343556 and states that the documents of the file disappeared during the Second World War (source 2).
At the 1909 Leipzig fair, more than 1,200 filters found buyers (source 1). The “Melitta” trademark was registered in 1911 (source 2). In 1929, the company left Dresden for a former chocolate factory in Minden, and became Melitta-Werke AG in 1932 (source 5).
The cone comes from there. Patent DE 652010, filed on June 7, 1936, starts from a flaw in cup-shaped filters: a triangular paper pocket fits a round bottom poorly, is supported only at the center, and tears at the edge when the column of liquid weighs on it. The answer is an oval bottom that, at the limit, becomes a simple slot serving as the outlet, and a ribbed wall on which the paper rests everywhere (source 3). Patent DE 653796, of December 1937, folds the pocket from a half-circle sheet to save paper (source 4). When Hario drew its cone, these “boat” filters had reigned for more than half a century (source 12).
The motion
The seams of the filter are folded over, on the side then on the bottom, so that it fits the ribs; it is set in the filter holder above the carafe, the paper is wetted, then the grind is added and the water poured in several stages. The paper rests on the ribs and lets the water run down to the slot at the bottom, as the 1936 patent describes (source 3).
Because the opening is narrow, part of the water waits in the cone: the time depends on the grind and on the fines, those very small particles that clog the paper. The European Coffee Brewing Centre sets its reference grind for four to six minutes of contact (source 10).
The settings
- Grindmedium, set for 4 to 6 minutes of contact in the reference tests (source 10)
- Dose50 to 60 g of coffee per liter of water, the “standard” comparison ratio of the European center (source 10)
- Brew ratioabout 1:17 to 1:20, calculated from 50 to 60 g per liter (source 10)
- Temperature92 to 96 °C on contact with the grind (source 10)
- Time4 to 6 minutes (source 10); Melitta gives no duration in the pages read (source 5)
- Pressurenone: gravity alone
What it has going for it
- The paper holds back most of the diterpenes, those fatty compounds in coffee that raise cholesterol: filtered coffee contains only traces, against several milligrams per cup for boiled coffee (source 9).
- The filter is thrown away with the grounds, with no washing, which a testing-laboratory chemist already judged ideal in 1917, compared with the poorly maintained cloth bags of restaurants (source 6).
- The cup comes out clear: in the comparative tasting of 1917, the paper filter came first, ahead of cloth, glass, the percolator and the boiled pot (source 6).
- The ribbed cone supports the paper everywhere and avoids tearing at the edge, the flaw the 1936 patent was written to correct (source 3).
What is held against it
- Each cup uses up a filter, and reducing paper was already an argument of the 1937 patent (source 4).
- Papers are not all equal: those with microperforations let more cafestol through, and porosity matters as much as grind (source 8).
- An unbleached paper releases a little matter into the water if it is not rinsed, 5 ppm measured on a natural Hario filter against 0 for a bleached one (source 7).
- As early as 1917, paper was accused of holding back “precious elements” of the drink, a reproach only partly supported (source 6).
What it gives in the cup
Paper makes a clear cup, light in body: it stops the grounds, some of the oils and almost all the diterpenes (sources 8 and 9). Grind fineness and paper porosity set what gets through (source 8).
No measurement specific to the Melitta cone, of yield or concentration, was found. The University of California, Davis study on the taste of filter coffee according to its concentration, done on machine-brewed coffees (source 11), is summarized in the electric coffee maker sheet.
Anecdotes
- The documents of the 1908 utility model were lost during the Second World War; the drawing the German office shows today is a reconstruction from the wording (source 2).
- Ukers, in 1922, lists the American paper filters from 1905 to 1912 without ever naming Melitta, whose filters had been sold in Germany since 1908 (source 6).
The sources for this sheet
- DPMA (German Patent and Trade Mark Office), “Melitta Bentz' coffee filters,” page of the series on women inventors, accessed October 21, 2026 · online · primary
- DPMA, poster “Kaffeefilter, Melitta Bentz, Dresden 1908, Gebrauchsmuster Nr. 343556,” poster gallery, 2021 · online · primary
- Melitta-Werke AG, patent DE 652010 C “Aufbrühfilter,” filed June 7, 1936, granted October 23, 1937 · online · primary
- Melitta-Werke AG, patent DE 653796 C “Filterpapiereinsatz für Kaffeeaufbrühfilter,” granted December 3, 1937 · online · primary
- Melitta Group, “Our history,” pages 1908, 1929, 1932 and 1936 (according to the manufacturer), accessed October 21, 2026 · online · secondary
- William H. Ukers, All About Coffee, New York, 1922, ch. XXXIV (Casseneuve 1824) and ch. XXXVI (coffee made to order, Cauchois, Acker, Tricolator, the 1917 controversy and the Tea and Coffee Trade Journal test) · online · primary
- Jonathan Gagné, “An in-depth analysis of coffee filters,” Coffee ad Astra, August 4, 2019 · online · secondary
- M. Y. Rendón, M. B. dos Santos Scholz, N. Bragagnolo, “Physical characteristics of the paper filter and low cafestol content filter coffee brews,” Food Research International, 108, 2018, p. 280-285, doi:10.1016/j.foodres.2018.03.041 · online · primary · reading: abstract
- G. Gross, E. Jaccaud, A. C. Huggett, “Analysis of the content of the diterpenes cafestol and kahweol in coffee brews,” Food and Chemical Toxicology, 35 (6), 1997, pp. 547-554, doi:10.1016/s0278-6915(96)00123-8 · online · primary · reading: abstract
- European Coffee Brewing Centre (Norwegian Coffee Association), “Certification standards, professional,” accessed October 21, 2026 · online · primary
- S. C. Frost, W. D. Ristenpart, J.-X. Guinard, “Effects of brew strength, brew yield, and roast on the sensory quality of drip brewed coffee,” Journal of Food Science, 85 (8), 2020, p. 2530-2543, doi:10.1111/1750-3841.15326 · online · primary · reading: abstract
- Hario, “The origin of the V60” and “History of the V60 transparent dripper” (according to the manufacturer), accessed October 21, 2026 · online · secondary