The idea to combine steeping with drip-filtering was utilized by the Berlin-based coffee roaster Carl Artur Büttner (also written as Carl Arthur Büttner)[nb 1] in his 1926 invention of a manual zero-bypass flat bottom coffee maker consisting of four parts, all made out of porcelain: a filter pot (Filtergefäß / Oberteil, "O") with lid (Deckel, "D"), saucer (Ablaufteller / Unterteil, "U") and coffee pot (Kaffeekanne, "K").
The captured hot air causing mild micro-turbulences on the underside of the coffee grounds were said to help avoid clogging.
Steeping was achieved utilizing a valving mechanism stopping the flow through the filter by a specially designed rotatable saucer with a single hole,[8][9][10][11][12] which had to be positioned between the filter pot and the coffee pot so that the hole was initially closed and was manually opened when the coffee had been steeping for three to five minutes.
Marketed since spring 1927[5][6] and up into, at least, the 1940s, these coffee makers were available as stand-alone devices for home use, but were also adopted by various other German coffee roasters (including Maschinenfabrik Bremen (Bremen, Germany),[14][15] Georg Schrader & Co. aka Geschraco (Bremen, Germany), Ferd + Eichhorn [de] (Braunschweig, Germany), Heimbs & Sohn Co. [de] (Braunschweig, Germany) and Columbus (Germany)) as part of larger coffee machines produced by the porcelain manufacturer Bauscher [de] (Weiden, Germany) for heavy-duty semi-continuous batch use in restaurants and canteens.
The Büttner extraction method was boldly marketed claiming to be the world's best moka and coffee filter ("Der beste Mokka- und Kaffeefilter der Welt").