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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Pottery. History of invention and production
Directory / The history of technology, technology, objects around us The plastic properties of clay have been known to man since ancient times. She was easily crumpled and, under skillful hands, quickly took on a form that was very difficult or even impossible to give to other known materials. At the same time, it was discovered that after firing them in fire, clay products surprisingly change their properties - they acquire stone hardness, water resistance and fire resistance. All this made clay the most convenient raw material for making dishes and kitchen utensils. Like all crafts, the technique of ceramics has come a long and difficult way. Thousands of years have been spent on studying the advantages and disadvantages of various clays. Of the many types of them, the ancient masters learned to choose those that were distinguished by the greatest plasticity, coherence and moisture capacity. Various additives were added to the clay mass to improve the quality of products (for example, coarse or fine sand). At the same time, ancient potters mastered various methods of modeling. It was not easy to give a piece of raw clay the shape of a jug, or even a simple pot. Usually, the potter, taking a lump of clay, sculpted the bottom by squeezing out its middle part and carefully squeezing the sides. Then the master began to stick rolled out strips of clay to the edge of the bottom, and so he gradually got the walls. In the end, a crude vessel came out, suitable after being burned at the stake for cooking food in it.
An important step in the development of pottery was the development of the technique of rotation. In this case, the master stuck a piece of clay to the finished bottom and, rotating the bottom with his left hand, circled the piece in a spiral with his right, gradually sculpting the edges of the pot. With this method, the product came out more even. Later, for the convenience of work, a wooden disk was placed under the workpiece. Then they came to the idea that the modeling process would be greatly simplified if this disk was made to rotate along with the workpiece - this is how the simplest manual potter's wheel was invented. It was a disc deepened in the middle by about half its thickness. With its recess, the disk was mounted on a protruding and somewhat rounded end of a wooden rod, firmly fixed in the ground. In order for the rod not to stagger and to hold a vertical position, a fixed wooden board with a hole in the middle was placed between it and the circle. It turned out to be a well-fitted device. With one hand, the master brought the circle into a smooth uniform rotation, and with the other he began sculpting. This simple device made a real revolution in pottery, raising it to the level of art. Thanks to him, the work has noticeably accelerated and improved. When rotated, the products came out much more dense and uniform. Their form turned out to be correct and elegant.
A new step towards the improvement of pottery was the invention of the foot circle, which came into use in the 2nd millennium BC. Its main advantages were that it allowed several times to increase the speed of rotation and freed the master to work with both hands. The main differences of the new circle were as follows. The spindle (axis of rotation) has been lengthened. The rotating disk was rigidly connected to it. Two boards served to strengthen the spindle. The lower one was the basis of the entire device (a recess was cut into it, where the end of the spindle was inserted). The top board with a through hole supported the spindle in a vertical position. Finally, a foot wheel was rigidly attached to the bottom of the spindle. Sitting next to the circle, the potter leaned his foot on the lower circle and brought it into smooth motion. Due to the fact that the lower wheel was heavier and larger in diameter than the working upper one, it acted as a flywheel: it retained rotation for some time even after the foot was removed from it.
Simultaneously with the improvement of the potter's wheel, there was a complication of the technique of firing clay. In ancient times, firing was carried out directly on an open fire at a temperature of 300-400 degrees. Later it began to be produced in special ovens. Already the first primitive furnaces made it possible to double the heating temperature. Clay particles began to fuse with each other better, the strength of the products increased markedly.
The former thick-walled vessels are being replaced by vessels with walls as thin as eggshells (up to 3 mm). The invention of furnaces was of great importance for the history of technology, as it marked the beginning of the construction of high-temperature devices, which then became widespread in other sectors of the economy (primarily in metallurgy).
The stove was made as follows: a wooden frame was made from thin trunks, which was coated with a thick layer of clay, only leaving small holes in places. This frame was placed over a recess, which was a place for kindling a fire. From a strong fire, the wooden parts burned down, and the clay was burned and formed a dense hearth with holes. During firing, the under and walls of the furnace became red-hot and also began to radiate heat. Due to the concentration of heat inside the furnace, the temperature in it could rise to 800 and even up to 900 degrees. Author: Ryzhov K.V.
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