mardi 6 novembre 2012

The Factory That Used To Make Porcelain

Porcelain was obtained in China in 620 and its way of manufacture was kept in secret for many years. European porcelain was obtained much later. In Belarus they have an old factory that keeps manufacturing porcelain in spite of the fact its equipment needs to be replaced for modern one. The process of porcelain manufacturing is very complex and is shown below.

The history of porcelain started in 1883 when pottery industry was started in one of the streets of Belarus.
In 1920 the factory was owned by the Minsk city council of workers and soldier’s deputy. The enterprise was developed fast that time.
After Minsk was freed from the Nazi occupants the factory had to be reconstructed. In 1946 it started producing angular glazed and unglazed tiles.
A gas generator was exploited in 1950 making ceramic baking more successful. Qualitative changes of technological processes lead to re-profiling of the factory that was now busy with porcelain making. 15 March 1951  is the birthday of Belarus porcelain.
The mechanized plant that had to produce 5,4 million pieces of cutlery was put into effect in 1979.
A block of additional works with the area of 6000 square meters was put into effect in 1983. The factory continued its development till 1990.
Today the following works are located on the territory of the factory: hollow construction shop, flat constructions shop, radioceramics shop, firebrick shop and laboratories.
The factory was closed in 2009. According to the official reason, it operated at a loss for many years.
Year of production 1977, item number 8, order number 2031210, mass 5157 kg (11370 ft).
Broken items are used in production of fresh molding material.
The raw material is taken to the factory by car. Kaolin contains electrolytes and coagulants that can negatively influence the quality of porcelain items. That is why it is cleaned and goes through the stage of filtration.
Quartz sand is sifted, can be dried in case of high humidity and then loaded into a drum.
Flat constructions are formed in submachines. They are cut into 20-25 pieces in one movement. Then the item is put into an empty mould heading to the forming roller. The steering circle rotates counterclockwise and stops every 90 degrees. The mass is moved together with the mould and this is how an object is made.
The forming roller is heated to prevent adhesion of the mass. Flat and hollow items have different mould forms.
Complex objects such as sculpture, vases, etc. can be made by casting only. The essence of the casting consists in the ability of gypsum to dehydrate the suspension of porcelain mass.
Additional parts like handles are casted separately and then glued to the body of the item. The details can be formed simultaneous with the frame of the item.
After moulding the objects needs to get dried to carry out the following operations.
The first baking step is used to make the half-ready item strong and free from organic mixtures.
A porcelain semi-product acquires the necessary properties such as mechanical strength, gas- and water tightness, thermal stability only after glaze firing in high temperature.
During the large firing step temperature increases slowly. The final firing temperature is 1340-1380 degrees Celsius (2444-2516 F).
Tunnel furnace.
Porcelain items are treated in furnaces for 27-35 hours.
Items in the furnace must be isolated from the free flame to avoid overburning.
Color glaze is one of the methods of item decoration.
Brush painting.
The depth of the paint layer must not exceed 40 m to be well-fixed on the surface.
A drawing is coped through a tracing paper with a pencil. Then they put the paper on a piece of cloth and make small holes along the outlines so that the holes wouldn’t be located too close to one another. The paper with small holes is straightened rubbing with pumice.
After that the tracing paper is put onto the porcelain item and graphite is rubbed through the orifices. As soon as the paper is removed, a pattern outline in the form of weak lines is left on the item.
In 1999 a group of German engineers visited the factory and found the equipment old-fashioned. They also offered another modern project. But the executives of the factory refused their offer.

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