General Condition Terms for Ceramics the Purpose of This Glossary Is To
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General Condition terms for Ceramics The purpose of this glossary is to provide you with a common language for the condition of ceramic items. Hardness the hardness of a ceramic is dependent on the type of clay used, its porosity and firing temperature. The following are simples classifications. Greenware Unfired clay articles. Earthenware- A glazed porous ceramic created by low temperature firing. Majolica or maiolica is tin glazed earthenware and overpainted with oxides developed in Majorca. Similar pottery is known in France as Faience and the UK as Deftware. Porcelain- Kaolin based ceramic body that has been fired between 1200oC- 1400°C vitrifying the composition becoming non porous Bisque-unglazed porcelain Flaws Flaws are defects, visible marks or inclusions made during the manufacturing process that should be included in the description. Damage Damage describes defects made through use, handling, cleaning or storage. Damage includes nicks, cracks, scratches, paint wear and crazing. Abrasion – Scuff marks or areas of concentrated scratches, generally caused by rubbing against another item over time. Accretions-build up or deposit of a foreign materials on a surface Efflorescence-white powdery or hard salt deposits that are located on the surface of the ceramic Spalling- loss from the separation of the ceramic layers due salts migrating through the body and glaze Flaking –lifting and separation of the glazing from the ceramic body without complete loss of the insecure area Light scratches - Scratches which do not score the surface of the item. Can be seen but not felt. Deep scratches - Scratches which score the surface of the item and can be felt with a fingernail. Deep scratches should be measured in inches in the definition. Chips – surface losses greater than 1/4” which are close to the surface of an item. Deep chips – losses greater than ¼” which can be easily felt with a finger. Nicks - chips of less than 1/4” Pinpoint nick - Tiny fairly round little nick no larger than the size of a pencil point. Gold, platinum or silver wear - Wear to the decorative metallic trim on an item. Wear may be Speed Dating Ceramic general condition terminology Page 1 described in estimated percentages - as in, “gold trim is approximately 90% intact.” Decal deterioration - Wear or disintegration of an under the glaze decorative decal. Paint wear - Wear to painted decoration applied after manufacture. In pottery, this is often referred to as “cold paint” wear. May be described in estimated percentages - as in, “approximately 20% overall paint wear.” Crack - A fracture which goes completely through the body Hairline crack - A very tight, fine, narrow crack Stains - discoloration that has altered the original color. Stains can be under the glaze, usually surrounding a flaw, or over the glaze. Crazing - A network of spidery cracks in the surface of the glaze. May be described in estimated percentages or by location - as in, “light crazing over 100% of the item” or “heavy crazing on the pedestal only.” Crawling. A parting and contraction of the glaze on the surface of ceramic ware during drying or firing, resulting in unglazed areas bordered by coalesced glaze. Mold Mark - Rough, raised mold lines or seams which were not smoothed during manufacture. Glaze Pop - Small round hole in the glaze formed when a small bubble of glaze popped during firing. Glaze Skip - A place where the glaze did not cover the pottery during manufacture. May show as unglazed pottery or may have a final, shiny glaze over it. Stilt Marks - Tiny unglazed bubbles on the underside of pottery that was suspended on stilts during firing. There are usually three in a triangular pattern. Kiln Kiss - A small spot where the piece touched another piece in the kiln, leaving a small “pimple”. Join voids- areas where added elements have separated when dried Speed Dating Ceramic general condition terminology Page 2 .