Sunday, October 22, 2017

Oh, patents! Melitta® filters

Copyright © Françoise Herrmann

Ever wondered who might have invented Melitta® paper filters for brewing coffee, or any of the hundreds of non-electric, "pour over and drip", coffee brewing Melitta® products, with a green and red package?

Her name is Melitta Bentz! She was born in Dresden, Germany, in 1873, where she invented round paper filters for brewing coffee that she placed on the bottom of a  perforated pot. Her eponymous invention solved two pervasive problems of the prior art: the bitterness of the grounds floating in coffee brews, and the impossible tasks of cleaning cloth coffee filters. Inspired by blotting paper used in schools, her paper filter was apparently first patented in Germany on July 8, 1908.  Her company M. Bentz was registered in Dresden in December 1908.

The rest is history! A search at the EPO for “Melitta Bentz” returned more than 400 patents, the most recent of which are still perfecting the art of paper filters for brewing coffee.

The following are a few of the Melitta Bentz patents filed in Great Britain in the 1930s:

  • GB400077 (A) ― 1933-10-19 - Improvements in or relating to filtering devices
  • GB415929 (A) ― 1934-09-06 - Improvements in filtering devices particularly for coffee, tea or other beverages 
  • GB416299 (A) ― 1934-09-13 - Improvements in and relating to filter papers 
  • GB451197 (A) ― 1936-07-31 - Filter paper for filtering apparatus in cup form
  • GB494316 (A) ― 1938-10-24 - Improvements in paper filter bags for filter vessels
  • GB494312 (A) ― 1938-10-24 - A filtering device for beverages such as coffee and tea
The abstract for GB400007 is included below with the patent drawings showing the already funnel-shaped Melitta® filter, and its improved ribbed bottom. The purpose of this particular Melitta® filter patent was to increase the speed of filtration of such substances as coffee, tea, malt and coffee substitutes. Prior art paper filters pressed against the bottom of the filter under the weight of the substances being filtered and thus contributed directly to the decreased speed of filtration. This particular Melitta® filter invention seeks to resolve decreased filtration speed caused at the bottom of the filter, with a ribbed bottom, so that the recesses formed together with the ridges create passages leading to the openings, found on the bottom of the filter. Similarly, the filter also has ribbed walls, designed to drain filtrates to the bottom of the filter containing openings.
A filter h having ribs i  on tapered side walls is provided with a flat bottom k having ribs l forming passages therebetween leading directly to one or more outlets m on the bottom, some, at least, of the passages between the ribs i leading directly into the passages in the bottom. Circular or other holes or slots may be provided in the side walls. The filter may be made of aluminium or of ceramic material and may be supported in a conical flanged holder or by a ring n formed integral with the filter. A further support o may be provided whereon the filter is rotatably mounted such that the orifices m may coincide with projections q or with orifices in the support for closing or opening the outlet from the filter. The filter paper may be introduced by a conical tool. [Abstract GB400007]  
Melitta Group

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