Millstone


Millstones or mill stones are stones used in gristmills, used for triturating, crushing or, more specifically, grinding wheat or other grains. They are sometimes referred to as grindstones or grinding stones.
Millstones come in pairs: a stationary base with a convex rim known as the bedstone and a concave-rimmed runner stone that rotates. The movement of the runner on top of the bedstone creates a "scissoring" action that grinds grain trapped between the stones. Millstones are constructed so that their shape and configuration help to channel ground flour to the outer edges of the mechanism for collection.
The runner stone is supported by a cross-shaped metal piece fixed to a "mace head" topping the main shaft or spindle leading to the driving mechanism of the mill.

History

The origins of an industry

Often referred to as the "oldest industry", the use of the millstone is inextricably linked to human history. Integrated into food processes since the Upper Palaeolithic, its use remained constant until the end of the 19th century, when it was gradually replaced by a new type of metal tool. However, it can still be seen in rural domestic installations, such as in India, where 300 million women used hand mills daily to produce flour in 2002.
The earliest evidence for stones used to grind food is found in northern Australia, at the Madjedbebe rock shelter in Arnhem Land, dating back around 60,000 years. Grinding stones or grindstones, as they were called, were used by the Aboriginal peoples across the continent and islands, and they were traded in areas where suitable sandstone was not available in abundance. Different stones were adapted for grinding different things and varied according to location. One important use was for foods, in particular to grind seeds to make bread, but stones were also adapted for grinding specific types of starchy nuts, ochres for artwork, plant fibres for string, or plants for use in bush medicine, and are still used today. The Australian grindstones usually comprise a large flat sandstone rock, used with a top stone, known as a "muller", "pounder", or pestle. The Aboriginal peoples of the present state of Victoria used grinding stones to crush roots, bulbs, tubers, and berries, as well as insects, small mammals, and reptiles before cooking them.

In Ancient history

Careful examination of Paleolithic grinders enables us to determine the nature of the action exerted on the material and the gesture performed; the function of the tool can then be specified, as well as the activity in which it participated.
Neanderthal people were already using rudimentary tools to crush various substances, as attested by the presence of rudimentary grinders at the end of the Mousterian and millstones in the Châtelperronian. From the Aurignacian period onwards, Cro-Magnon man regularly used millstones, elongated grinders, and circular wheels. From the Gravettian period onwards, this equipment became more diversified, with the appearance of new types of tools such as millstones and pestle grinders.
At the end of the Palaeolithic, millstones from Wadi Kubbaniya were involved in dietary processes and associated with residues of tuberous plants, which were known to require grinding before consumption, either to extract their toxins, or to remove the fibrous texture that would make them indigestible. The rhizomes of ferns and the peel of the fruit of the doum palm, also found on this site, benefit from being ground to improve their nutritional qualities; they thus complemented the meat diet of hunter-gatherers. Grinding barley or oat seeds was practiced at the end of the Upper Palaeolithic or the Kebarian.
As tools improved, the material was increasingly finely ground, but only when it became a real powder could we speak of grinding. Thus, the men of the European Upper Paleolithic were already dissociating grinding and milling, as attested by the appearance at this time of the first grinding slabs used with grinders or millstones. While there is no evidence of the milling of wild cereals in the early Upper Paleolithic, at least in Europe, there is no reason not to believe that other plant matter and animal matter were already being ground into paste before cooking. Similarly, it's likely that millstones were being used at this time for technical purposes, to crush mineral substances and certain plant or animal fibers for technical use.
File:CMOC_Treasures_of_Ancient_China_exhibit_-_millstone_and_roller.jpg|left|thumb|Stone-grinding slab with grinding roller Peiligang culture, Xinzheng
In the Mesolithic and Neolithic eras, with the domestication of plants, much larger, fully formed grinding, pounding, and milling equipment appeared. From the Natufian onwards, several types of millstones can be found side by side, such as the deep "trough-shaped" millstone or the flat millstone, indicating a specialization of their function. In the Near East, the pestle-grinder began to be developed in the Kebarian and Natufian periods. It gradually evolved into the heavy, generally wooden, thrown pestle. This type of equipment is still used today in many regions, such as in Ethiopia for milling millet.
The appearance of flat, elongated millstones in the Natoufian period dates back to the 9th millennium BC. They feature larger active surfaces and mark the emergence of a new gesture, that of grinding from front to back, with both hands, which implies a new posture for the body, kneeling in front of the millstone. The appearance of large, asymmetrical, shaped millstones led to the "saddle-shaped" millstones still known today as the metate.

In the rest of the world

At the Tell Abu Hureyra archaeological site, as early as the 8th millennium BC, women's skeletons show traces of osteoarthritis in the knees, spinal deformity and deformation of the first metatarsal, pathologies associated with long periods of bending while grinding, supporting the theory that early humans practiced a sexual division of labor.
In India, millstone were used to grind grains and spices. These consist of a stationary stone cylinder upon which a smaller stone cylinder rotates. Smaller ones, for household use, were operated by two people. Larger ones, for community or commercial use, used livestock to rotate the upper cylinder. Today a majority of the stone flour mills are equipped with lower stone rotating and upper stone stationary millstones also called Shikhar Emery Stones which are made from abrasive emery grains and grits, with a binding agent similar to Sorel Cement. These stones are made from two types of emery abrasives - Natural Jaspar Red Emery or Synthetic Calcined Bauxite Black Emery.Image:Walderveense molen steenbillen.jpg|upright|thumb|Dressing a millstone
In Korea, there were three different millstones, each made from different materials, serving other purposes, such as threshing, grinding, and producing starch. Generally, the handle of a millstone in Korea was made from an ash tree, the process for making a handle from the ash tree was known as "Mulpure-namu". To ensure that everything is "all right" with the creation of a millstone, a mason within ancient Korea offered food and alcohol in a ritual.
Millstones were introduced to Britain by the Romans during the 1st century AD and were widely used there from the 3rd century AD onwards.
In 1932-1933 in Ukraine, during the man-made famine known as Holodomor, the Soviet authorities prohibited the use of millstones, claiming that a millstone is a "mechanism for enrichment". This forced Ukrainian villagers to hide their manually operated millstones and use them secretly during the famine. In response, Soviet authorities regularly searched villages for "illegal" millstones and destroyed them. In 2007, the people of Victorivka village in Cherkasy Oblast built a monument using the millstones they had managed to hide and save from the Soviet plunder during the Holodomor.

Different techniques: grinding, crushing, milling

The preparation of vegetable products, animal products, or mineral products by grinding or milling, for consumption or technical use, has existed for several dozen millennia. Unlike crushing, in which a hard envelope such as a shell or bone is broken open to recover its contents, in this case, the aim is to reduce a much softer material to a powder or paste.
Depending on the place and time, millstones were used for "dry" grinding: in the manufacture of flour, sugar, or spices, but also for the preparation of kaolinite, cement, phosphate, lime, enamel, fertilizer, and other minerals. The milling operation can also be carried out "wet", as in the case of durum wheat semolina, nixtamal, or the grinding of mustard seeds. During preparation, some raw materials produce a naturally fluid paste, as in olive crushing or cocoa grinding.
In his typology of percussion, André Leroi-Gourhan defines several families of gestures, three of which are essential for the preparation of raw materials:
  1. Crushing gestures involve vertical percussion using a heavy, elongated object in the manner of the African pestle. This gesture is also used by the trip hammer to make paper pulp, or in forging;
  2. Milling gestures, using percussion, which are performed in a circular, disordered, or back-and-forth motion on a millstone;
  3. Grinding gestures, in which the movements are roughly circular and occasionally vertical, thus combining a thrown percussion and a percussion posed, are qualified here as diffuse. This is the case with the contemporary mortar-pestle system.

    Milling systems

Until the invention of the watermill, mills operated using "strength-powered", i.e. the force of animals or people.

The metate

The metate is a nether millstone for domestic use, for grinding corn. It has been used for several thousand years in the cultural area of Mesoamerica, and its name comes from the Nahuatl "metatl".
Today's millstones are monolithic, usually made of basalt, apodous, or tripod, rectangular, and slightly concave on the grinding surface. These millstones are associated with a two-handed wheel, called a "mano", whose size generally exceeds the width of the millstone and which is driven in an alternating rectilinear motion. On tripod wheels, one of the legs is slightly higher than the other two, giving the whole unit an inclination, with the user standing in front of the highest part.
The manufacture of millstones was essentially a male occupation. In pre-Hispanic times, millers used only stone tools, a practice that persisted in some villages until the mid-20th century. The use of metal tools, probably inherited from building stonemasons, made it possible to use the hardest basalts, resulting in millstones with a lifespan of over thirty years. While the manufacture of apod millstones from blocks of stone naturally polished in a riverbed was once within the reach of many farmers, the production of tripode metates requires specialized craftsmanship.
Grinding plays a key role in Mexican cuisine. Dry grinding is possible, but very few recipes are produced in this way: roasted coffee, roasted corn or beans, salt, sugar loaves, and cocoa are ground into powder. But most preparations require grinding with water. Fruits are ground into juices, beans or boiled vegetables, ingredients are added to various spicy sauces and, above all, corn is used to make the tortillas that form the basis of every meal. The latter are made from nixtamal, i.e. dry corn kernels cooked with lime, then rinsed with water, which softens the kernels and produces a paste. Maize or nixtamal can be ground for preparations other than patties: tamales, pozole, atole, pinole, and masa, with variations in the fineness of the grind depending on the use.
File:TortillaMakingSalvador.jpg|left|thumb|Tortilla-making in El Salvador, circa 1900
The metate was used exclusively by women, and in Mixtec lands, the place where the millstone is located was a space reserved for women. A couple often acquires, or is given, a millstone when they set up home. This acquisition represents a major expense in the life of a Mixtec peasant, as evidenced by the wills of nobles and wealthy peasants from the 16th to 18th centuries, which included metates.
Daily tortillas are made from sufficiently moistened corn dough, which, unlike flour, cannot be preserved. This technical characteristic no doubt explains why domestic metates were not replaced centuries ago by mills, as they were in Europe. During the wars of the 19th century and the Mexican Revolution of 1910, Mexican armies were accompanied by women and metates to ensure the stewardship of the country; the Spanish conquest did not replace tortillas with bread - quite the contrary. At the end of the 19th century, the owners of the large plantations introduced motorized corn mills, which freed up female labor for the fields. From 1920 onwards, electric mills appeared in the countryside, owned by municipalities, cooperatives or private individuals. However, still in use today, nether millstones are still part of Mexico's rural heritage.