Tin-glazing 4583836 224769161 2008-07-10T09:55:54Z Lightbot 7178666 Units/dates/other '''Tin-glazing''' is the process of giving [[ceramic]] items a tin-based [[ceramic glaze|glaze]] which is white, shiny and opaque, normally applied to red or buff [[earthenware]]. The earliest [[tin-glazed pottery]] appears to have been made in [[Iraq]]/[[Mesopotamia]] in the 9th century, the oldest fragments having been excavated during the [[First World War]] from the palace of [[Samarra]] about fifty miles north of [[Baghdad]].<ref>Caiger-Smith, 1973, p.23</ref> From Mesopotamia it spread to Egypt, Persia and Spain before reaching [[Italy]] in the [[Renaissance]], [[Holland]] in the 16th century and [[England]] and [[France]] shortly after. Tin-glazed pottery fell out of common use in the 18th century after [[Josiah Wedgwood]] formulated a very white earthenware body. There has been a revival in the twentieth century by [[studio pottery|studio potters]]. Some twentieth-century artists painted on tin-glazed pottery, for example, [[Picasso]], who produced much work of this kind in the 1940s and 1950s. [[Tin oxide]] (IV), has found widespread use in glaze, where it has been valued as an [[opacifier]]. Tin oxide can remain in suspension in the vitreous matrix, and, with its Refractive Index being sufficiently different from the matrix light is scattered, and hence increases the [[Opacity (optics)|opacity]] of the glaze. Due to the high cost of tin oxide many glaze formulations now use other opacifiers, such as [[zircon]] The earliest [[Middle East]]ern tin glazes used [[calcium]], [[lead]] and [[sodium]] [[compounds]] as fluxes in combination with the [[silica]] in sand. Piccolpasso recorded several glazes used in Italy in the 1550s, all variations of lead, tin, lime, soda and potash glazes. It is believed early Spanish glazes were similar.<ref>Caiger-Smith, 1973, p.207</ref> A more contemporary tin-glaze recipe is given by [[Alan Caiger-Smith]]:<ref> Caiger-Smith, 1973, p224</ref> *[[Lead]] bisilicate [[frit]]: 74% *[[China clay]]: 10% *[[Calcium carbonate|Whiting]]: 2% *[[Flint]]: 4% *[[Tin oxide]]: 10% Tin-glazed pottery is almost all decorated, which its white surface lends itself to. The decoration is applied as metallic oxides, most commonly [[cobalt oxide]], [[copper oxide]], [[iron oxide]], [[manganese dioxide]] and [[antimony]] oxide. Late Italian [[maiolica]] blended oxides to produce detailed and realistic polychrome paintings, called ''istoriato''. To these oxides modern potters are able to add powdered ceramic colours made from combinations of oxide, sometimes [[frit]]ted.<ref>[http://www.pottersconnection.co.uk/shop/33/index.htm Potters Connection]</ref> The pottery vessels are given a [[bisque]] or biscuit firing, usually between 900 deg C and 1000 deg C, which makes them strong but porous. The fired vessel is dipped in a liquid glaze [[Suspension (chemistry)|suspension]] which sticks to it, leaving a smooth and absorbent surface when dry. On this surface colours are applied by brush, the colours made from powered oxides mixed with water to a consistency of water-colour paint, sometimes with the addition of a binding agent such as [[gum arabic]]. The unfired glaze absorbs the pigment like [[fresco]], making errors difficult to correct but preserving the brilliant colors of the oxides when fired. The glazed and decorated vessels are returned to the kiln for a second firing, usually between 1000 and 1120 deg C (the higher temperatures used by modern potters). Lustered wares have a third firing at a lower temperature, necessitating a delicate control of the amount of oxygen in the kiln atmosphere and therefore a flame-burning kiln. Traditional kilns were wood firing, which required the pots to be protected in the glaze and luster firings by [[saggar]]s or to be fired in a [[muffle]] kiln. Except for those making luster ware, modern tin-glaze potters use electric kilns. ==References== *Caiger-Smith, Alan, ''Tin-Glaze Pottery in Europe and the Islamic World: The Tradition of 1000 Years in Maiolica, Faience and Delftware'' (Faber and Faber, 1973) ISBN 0-571-09349-3 *Caiger-Smith, Alan, ''Lustre Pottery: Technique, Tradition and Innovation in Islam and the Western World'' (Faber and Faber, 1985) ISBN 0-571-13507-2 *Carnegy, Daphne, ''Tin-glazed Earthenware'' (A&C Black/Chilton Book Company, 1993) ISBN 0-7136-3718-8 *Harris, David, ''Guide To Looking At Italian Ceramics'' (J. Paul Getty Museum in association with British Museum Press, 1993) *McCully, Marylin (ed.), ''Picasso: Painter and Sculptor in Clay'' (Royal Academy of Arts, 1998) ISBN 0-900-94663-6 *Piccolpasso, Cipriano, ''The Three Books of the Potter's Art'' (trans. A.Caiger Smith and R.Lightbown) (Scolar Press, 1980) ISBN 0-859-67452-5 <references/> ==See also== [[Tin-glazed pottery]] [[Category:ceramics]]