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The vibrancy that only underglaze was able to supply is now achievable with a variety of over-glazes therefore discounting the advantage that underglaze commercial production had. A well-known New York underglaze tile and pottery decorator of the 1940s, Carol Janeway (1913-1989), was diagnosed with lead poisoning after eight years of using a ...
In clay bodies a flux creates a limited and controlled amount of glass, which works to cement crystalline phases together. Fluxes play a key role in the vitrification of clay bodies by lowering the overall melting point. The most common fluxes used in clay bodies are potassium oxide and sodium oxide which are found in feldspars.
Glazes need to include a ceramic flux which functions by promoting partial liquefaction in the clay bodies and the other glaze materials. Fluxes lower the high melting point of the glass forms silica, and sometimes boron trioxide. Raw materials for ceramic glazes generally include silica, which will be the main glass former.
The wucai technique was a similar combination, with underglaze blue used more widely for highlights. [69] Two-colour wares, using underglaze blue and an overglaze colour, usually red, also produced very fine results. A number of different other methods using coloured glazes were tried, often with images lightly incised into the body.
Italian Renaissance maiolica, Faenza, istoriato ware by Baldassare Manara, after Giovanni Antonio da Brescia, c 1520 -47. In-glaze or inglaze is a method of decorating pottery, where the materials used allow painted decoration to be applied on the surface of the glaze before the glost firing so that it fuses into the glaze in the course of firing.
More recent trade began when a clay was needed to make tobacco pipes in the 16th and 17th century. [8] In 1771 Josiah Wedgwood signed a contract for 1,400 tons a year of ball clay with Thomas Hyde of Purbeck , enabling the production of thinner-walled ceramics.
The English name reflects the historical use of the material for fulling (cleaning and shrinking) wool, by textile workers known as fullers. [1] [2] [3] In past centuries, fullers kneaded fuller's earth and water into woollen cloth to absorb lanolin, oils, and other greasy impurities as part of the cloth finishing process.
In Canada, the clay is associated primarily with the Pleistocene-era Champlain Sea, in the modern Ottawa Valley, the St. Lawrence Valley, and the Saguenay River regions. [4] Quick clay has been the underlying cause of many deadly landslides. In Canada alone, it has been associated with more than 250 mapped landslides.