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The development of a translucent low fired porcelain casting slip using South African raw materialsRuiters, Mellaney Bualin January 2017 (has links)
The purpose of the research was to develop a translucent low fired porcelain casting slip using South African raw materials, due to the ever increasing electricity tariffs in South Africa as well as the physical deterioration put on the elements and brickwork in electric kilns when fired to traditional porcelain temperatures. Traditional porcelain bodies that can be purchased from South African suppliers are required to be fired to between 12000C and 13000C. The commercially prepared porcelains when tested produced white vitrified bodies but were lacking in translucency. Local ceramic artists are therefore compelled to import their porcelains from overseas suppliers if they require a white translucent porcelain but this is still requires a firing temperature well above 12000C. It has been shown that by using South African ceramic raw materials and adjusting a Parian ceramic formula using a selected frit; a low fired translucent porcelain can be made that matures below 12000C. The addition of paper fibres to the non-plastic porcelain was necessary to reduce the high shrinkage rate and prevented the clay from cracking and tearing in the firing process. With the further adjustments to the formula by the addition of calcium triphosphate true white translucent porcelain was produced. Without this last adjustment the porcelain would be an off-white colour due to the impurities found in the South African ceramic raw materials which are mainly contaminated with iron oxide. It was found that the following formula produced a white translucent porcelain which vitrified at 11900C and satisfies the original concept in the title stated above.
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