page_title: Ceramic glaze
section_title: Process
hierarchical_section_title: Ceramic glaze / Process
caption_attribution_description: İznik tiles in the Neo-classical Enderûn Library (Enderûn Kütüphanesi), also known as Library of Sultan Ahmed III (III. Ahmed Kütüphanesi), is situated directly behind the Audience Chamber (Arz Odası) in the centre of the Third Court of the Topkapi Palace in Istanbul.
context_page_description: Ceramic glaze is an impervious layer or coating of a vitreous substance which has been fused to a ceramic body through firing. Glaze can serve to color, decorate or waterproof an item. Glazing renders earthenware vessels suitable for holding liquids, sealing the inherent porosity of unglazed biscuit earthenware. It also gives a tougher surface. Glaze is also used on stoneware and porcelain. In addition to their functionality, glazes can form a variety of surface finishes, including degrees of glossy or matte finish and color. Glazes may also enhance the underlying design or texture either unmodified or inscribed, carved or painted.
  Most pottery produced in recent centuries has been glazed, other than pieces in unglazed biscuit porcelain, terracotta, or some other types. Tiles are almost always glazed on the surface face, and modern architectural terracotta is very often glazed. Glazed brick is also common. Domestic sanitary ware is invariably glazed, as are many ceramics used in industry, for example ceramic insulators for overhead power lines.
  The most important groups of traditional glazes, each named after its main ceramic fluxing agent, are:
context_section_description: Glaze may be applied by dry-dusting a dry mixture over the surface of the clay body or by inserting salt or soda into the kiln at high temperatures to create an atmosphere rich in sodium vapor that interacts with the aluminium and silica oxides in the body to form and deposit glass, producing what is known as salt glaze pottery. Most commonly, glazes in aqueous suspension of various powdered minerals and metal oxides are applied by dipping pieces directly into the glaze. Other techniques include pouring the glaze over the piece, spraying it onto the piece with an airbrush or similar tool, or applying it directly with a brush or other tool.
  To prevent the glazed article from sticking to the kiln during firing, either a small part of the item is left unglazed, or it is supported on small refractory supports such as kiln spurs and Stilts that are removed and discarded after the firing. Small marks left by these spurs are sometimes visible on finished ware.
caption: İznik tiles in the Enderûn Library, Topkapi Palace, Istanbul
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