Bone mill in Fretter

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The bone mill in Fretter belongs to the Ruhrmann farm; it worked mainly for the farm's own needs and only to a small extent for others. The mill building was probably built around 1900, but the cast-iron stamping mill is older. The use of artificial fertilizers spread with the development of transport by rail.

Knochenmühle Fretter

Knochenmühle Fretter Innenansicht


Bone mill in Fretter

Schöndelter Straße 11

57413 Finnentrop

Telefon: 02724/8258



The railroad line through the Fretter Valley was opened only in 1911 and due to the events of the following years, the home-made bone meal remained competitive for a long time: due to the lack of raw materials in the period of the First World War and the shortage of foreign exchange of the time after, the autarky policy of the "Third Reich", the events of the Second World War and the hesitant events after. Thus, this small building along with its equipment remained in operation until after the Second World War.

Technically, the bone mill is a stamping mill, as it has been used since the Middle Ages for many purposes, e.g. as an Ölmühle or for ore and slag extraction in mining and metallurgy. The bone mill in Fretter is one of only three still preserved in Westfalen. A special feature is the cast-iron tamping mill, the other two are made of wood. This is perfectly adequate for this purpose and also cheaper. Remodeling traces on the stamping mill of the Ruhrmannsmühle attest to changes that have been made.

A closer examination reveals that this is one of formerly two adjacent sets of a so-called "Californian Poche" in an early form from the time around 1860, as they were also used in the smelting works of this area as ore or slag poche. The presence of the sieve-like wick trough proves that the device was used for wet wick. The poke material could only be carried along by the flowing water when it was sufficiently crushed and fit through the perforation of the poke trough. In a connected channel with sedimentation troughs, the heavier ore was then separated from the lighter dead rock or the so-called wash iron from the slag. Thus, the stamping mill in Fretter is a unique testimony of the local mining industry in its second use. Possibly it originates from the Neubrücker Hütte, which existed on the site of the railroad station in Finnentrop from 1858 to 1907.

Even the "Deutsches Museum" in Munich owns only a much more modern form of such a Poche from 1902.

In the bone mill in Fretter, 30 to 40 hundredweight of bones, which had previously dried in the attic for one to two years, were pounded into flour in winter when work in the fields was at rest. The bone meal was mainly used for fertilizing the fields, but some was also added to the feed of young cattle and chickens.

Until the 19th century, three-field farming dominated the agricultural landscape of our region. The alternation of the cultivated land and the fallow were intended to give the soil a rest in order to preserve its fertility. Fertilization with manure or slurry took place only in horticulture. Thus, agriculture was not very productive, but very labor-intensive and fed only a few more people than were employed in it. Even those who practiced another profession were usually forced to farm alongside it.

The progress of natural sciences in the 19th century did not stop at agriculture. Professor Justus Liebig from Giessen discovered that certain minerals were particularly important for the development of plants: Phosphorus and potash. His conclusion that the quantities of these minerals consumed by plants must be returned to the soil each year in order to maintain its fertility can be seen as the beginning of artificial fertilization. Liebig's chemical investigations had shown that bones contain the most important minerals in a form suitable for plants, so it made sense to produce bone meal and spread it on the fields. However, this finding was not entirely new. Bone meal had been used as fertilizer in the British Isles, especially in Scotland, since the end of the 18th century. In Germany, the first bone mills for this purpose were established in Saxony and Silesia in the early 1830s. Bones now became a sought-after commodity. An encyclopedia from the mid-19th century complained that too much of it was exported to England instead of being used at home.

It was not until the end of the 19th century that bone meal began to face competition from the "Thomas slag" produced in the Thomas process of steel making, from guano transported in new bulk carriers from South America, and finally from artificial fertilizers supplied by the chemical industry.

Information and guided tours: Dorf- und Heimatverein Fretter e.V., Stefan Vogel, Am Weingarten 3, FinnentropFretter, Tel.: 02724/2439066

In the context of the German Mill Day (every Whit Monday: the bone mill is always integrated with demonstrations, grinding operation and hospitality.

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