Tin-glazing is the process of giving

tin-glazed pottery Tin-glazed pottery is earthenware covered in lead glaze with added tin oxide which is white, shiny and opaque (see tin-glazing for the chemistry); usually this provides a background for brightly painted decoration. It has been important in I ...

items a

ceramic glaze Ceramic glaze, or simply glaze, is a glassy coating on ceramics. It is used for decoration, to ensure the item is impermeable to liquids and to minimize the adherence of pollutants. Glazing renders earthenware impermeable to water, sealing th ...

that is white, glossy and opaque, which is normally applied to red or buff

earthenware Earthenware is glazed or unglazed Vitrification#Ceramics, nonvitreous pottery that has normally been fired below . Basic earthenware, often called terracotta, absorbs liquids such as water. However, earthenware can be made impervious to liquids ...

. Tin-glaze is plain lead glaze with a small amount of tin oxide added.Caiger-Smith, Alan, ''Tin-Glaze Pottery in Europe and the Islamic World: The Tradition of 1000 Years in Maiolica, Faience and Delftware'', London, Faber and Faber, 1973 The opacity and whiteness of tin glaze encourage its frequent decoration. Historically this has mostly been done before the single firing, when the colours blend into the glaze, but since the 17th century also using overglaze enamels, with a light second firing, allowing a wider range of colours.

Majolica In different periods of time and in different countries, the term ''majolica'' has been used for two distinct types of pottery. Firstly, from the mid-15th century onwards, ''maiolica'' was a type of pottery reaching Italy from Spain, Majorca a ...

maiolica Maiolica is tin-glazed pottery decorated in colours on a white background. The most renowned Italian maiolica is from the Renaissance period. These works were known as ''istoriato'' wares ("painted with stories") when depicting historical and ...

delftware Delftware or Delft pottery, also known as Delft Blue () or as delf, is a general term now used for Dutch tin-glazed earthenware, a form of faience. Most of it is blue and white pottery, and the city of Delft in the Netherlands was the major cen ...

and

faience Faience or faïence (; ) is the general English language term for fine tin-glazed pottery. The invention of a white Ceramic glaze, pottery glaze suitable for painted decoration, by the addition of an stannous oxide, oxide of tin to the Slip (c ...

are among the terms used for common types of

. An alternative is lead-glazing, where the basic glaze is transparent; some types of pottery use both. However, when pieces are glazed only with lead, the glaze becomes fluid during firing, and may run or pool. Colours painted on the glaze may also run or blur. Tin-glazing avoids these problems. The technique originated in the

Near East The Near East () is a transcontinental region around the Eastern Mediterranean encompassing the historical Fertile Crescent, the Levant, Anatolia, Egypt, Mesopotamia, and coastal areas of the Arabian Peninsula. The term was invented in the 20th ...

and reached Europe during the late

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...

, with a peak in Italian Renaissance

. It was never used in East Asian ceramics. Tin oxide is still valued in glazes as both an opacifier and as a white colorant. Tin oxide has long been used to produce a white, opaque and glossy glaze.’Ceramic Glazes’ Third edition. C.W.Parmelee & C.G.Harman. ''Cahners Books'', Boston, Massachusetts. 1973.‘Ceramics Glaze Technology.’ J.R.Taylor & A.C.Bull. ''The Institute Of Ceramics & Pergamon Press''. Oxford. 1986. As well as an opacifying agent, tin oxide also finds use as a colour stabiliser in some pigments and glazes. Minor quantities are also used in the conducting phases in some electrical porcelain glazes.

History

Chinese white ware and Iraqi earthenware bowls 9th 10th century both found in Iraq

The earliest tin-glazed pottery appears to have been made in

Abbasid The Abbasid Caliphate or Abbasid Empire (; ) was the third caliphate to succeed the prophets and messengers in Islam, Islamic prophet Muhammad. It was founded by a dynasty descended from Muhammad's uncle, Abbas ibn Abd al-Muttalib (566–653 C ...

Iraq Iraq, officially the Republic of Iraq, is a country in West Asia. It is bordered by Saudi Arabia to Iraq–Saudi Arabia border, the south, Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq border, the east, the Persian Gulf and ...

(750–1258) in the 8th century, fragments having been excavated during the First World War from the palace of

Samarra Samarra (, ') is a city in Iraq. It stands on the east bank of the Tigris in the Saladin Governorate, north of Baghdad. The modern city of Samarra was founded in 836 by the Abbasid caliph al-Mu'tasim as a new administrative capital and mi ...

about fifty miles north of

Baghdad Baghdad ( or ; , ) is the capital and List of largest cities of Iraq, largest city of Iraq, located along the Tigris in the central part of the country. With a population exceeding 7 million, it ranks among the List of largest cities in the A ...

. From Mesopotamia, tin glazes spread to Islamic Egypt (868–905) during the 10th century, and then to Andalusian Spain (711–1492), leading to the maximum development of Islamic lusterware.Mason, R. B., and M. S. Tite, "The beginnings of tin-opacification of pottery glazes", ''Journal of Archaeological Science'' 39:41-58, 1997 The history of tin glazes in the Islamic world is disputed. One possible reason for the earlier production of tin-glazed wares could be attributed to the trade between the Abbasid Empire and ancient China from the 8th to 9th century onwards, resulting in imitation of white Chinese

stoneware Stoneware is a broad class of pottery fired at a relatively high temperature, to be impervious to water. A modern definition is a Vitrification#Ceramics, vitreous or semi-vitreous ceramic made primarily from stoneware clay or non-refractory fire ...

by local Islamic potters. Another might be local glaze-making rather than foreign influence, supported by the similarity between the chemical and microstructural features of pre-Islamic white opaque glazes and that on the first tin-opacified wares Dutch delft tile topsham

From the Middle East, tin-glaze spread through the Islamic world to

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

. In the 13th century, tin glazes reached

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

, where the earliest recorded reference to their use is in the 1330s, resulting in the emergence of Italian

Maiolica Maiolica is tin-glazed pottery decorated in colours on a white background. The most renowned Italian maiolica is from the Renaissance period. These works were known as ''istoriato'' wares ("painted with stories") when depicting historical and ...

. Amongst others, Luca della Robbia, born in Florence about 1400, used tin oxide as an opacifier in glazes. Potters began to draw polychrome paintings on the white opaque surface with metallic oxides such as cobalt oxide and to produce lustreware. The off-white fired body of

Delftware Delftware or Delft pottery, also known as Delft Blue () or as delf, is a general term now used for Dutch tin-glazed earthenware, a form of faience. Most of it is blue and white pottery, and the city of Delft in the Netherlands was the major cen ...

and English

was made to appear white, and hence mimic the appearance of Chinese porcelain, by the application of a glaze opacified and coloured white by the addition of tin oxide. By the late 18th-century the reduction in the price of

porcelain Porcelain (), also called china, is a ceramic material made by heating Industrial mineral, raw materials, generally including kaolinite, in a kiln to temperatures between . The greater strength and translucence of porcelain, relative to oth ...

, and the new English creamwares and related types, stronger, lighter and often cheaper than traditional earthenwares, hit the production of tin-glazed wares very hard, and production of "useful" rather than decorative wares almost ceased, so that "by 1850 the industry was almost extinct" in France. In 1947 Arthur Lane wrote it was "now only ade in Europein a few places to provide the tourist with souvenirs"

Manufacturing process and colours

Though the recipe of tin glazes may differ in different sites and periods, the process of the production of tin glazes is similar. Generally speaking, the first step of the production of tin glazes is to mix tin and lead in order to form oxides, which was then added to a glaze matrix (alkali-silicate glaze, for example) and heated. After the mixture cooled, the tin oxide crystallises as what has been mentioned above, therefore generates the so-called white tin-opacified glazes. Besides, the body of tin-opacified wares is generally calcareous clays containing 15-25% CaO, of which the thermal expansion coefficient is close to that of tin glazes, thus avoid crazing during the firing process. On the other hand, the calcareous clay fired in an oxidising atmosphere results in a buff colour, thus lower the concentration of tin oxide used The white opaque surface makes tin glaze a good base for painted decoration. The decoration is applied as metallic oxides, most commonly

cobalt oxide Cobalt oxide is a family of chemical compounds consisting of cobalt and oxygen atoms. Compounds in the cobalt oxide family include: * Cobalt(II) oxide (cobaltous oxide), CoO * Cobalt(III) oxide (cobaltic oxide), Co2O3 *Cobalt(II,III) oxide Co ...

for blue, copper oxide for green,

iron oxide An iron oxide is a chemical compound composed of iron and oxygen. Several iron oxides are recognized. Often they are non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is rust. Iron ...

for brown,

manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cel ...

for purple-brown and

antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...

for yellow. Late Italian

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 fritted. In the sixteenth century, the use of subtle and blended colours which were not strong enough to penetrate the opaque glaze made the delicate control of tonal values possible, and the painting therefore had to be done on the glaze surface, which then becomes a common manner of painting on tin-glazed wares. This method was used until the 18th century, and is often called by the French name ''grand feu'' in English. The wares were fired twice, firstly just the clay body, then again after the glaze and painted colours were added. The colours applied on top of the glaze blended into it during firing (the technique thereby differing from

underglaze Underglaze is a method of decorating pottery in which painted decoration is applied to the surface before it is covered with a transparent ceramic glaze and fired in a kiln. Because the glaze subsequently covers it, such decoration is completely ...

painting used with transparent glazes). The disadvantage was that only a narrow group of pigments produced good colours after firing at the relatively high temperatures of up to . These included

cobalt blue Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with aluminium(III) oxide (alumina) at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt blue is lighte ...

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

dark purple,

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

green,

yellow, and the very tricky iron reds and brown, which only some potters were able to make as a good red. In the 18th century overglaze enamels began to be used in the same way as on

; this technique is often called ''petit feu'' in English when talking about faience (the Italian name is ''piccolo fuoco''). A much wider range of colours was possible, but after the fired and glazed wares were painted a third firing was required, at a lower temperature of perhaps . In modern versions, the pottery vessels are biscuit fired, usually between . The fired vessel is dipped in a liquid glaze 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 Gum arabic (gum acacia, gum sudani, Senegal gum and by other names) () is a tree gum exuded by two species of '' Acacia sensu lato:'' '' Senegalia senegal,'' and '' Vachellia seyal.'' However, the term "gum arabic" does not indicate a partic ...

. The unfired glaze absorbs the pigment like

fresco Fresco ( or frescoes) is a technique of mural painting executed upon freshly laid ("wet") lime plaster. Water is used as the vehicle for the dry-powder pigment to merge with the plaster, and with the setting of the plaster, the painting become ...

, 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 °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 saggars or to be fired in a muffle kiln. Except for those making luster ware, modern tin-glaze potters use electric kilns. The recrystallisation of tin oxide during the firing provides evidence of the slightly different methods of different production sites, as the crystal size, the distribution and the concentration may be influenced. For instance, the analysis of the 14th century Islamic tin glazes from eastern Spain indicates that these samples may be produced by non-fritting methods, as the heterogeneous distribution of tin oxides may be the remains of original grains of tin oxides. The interaction between glaze and body also give clues to different handling and firing processes. As mentioned above, tin glaze suspension is applied to bisque or biscuit body made of calcareous clay with high content of

calcium oxide Calcium oxide (formula: Ca O), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term '' lime'' connotes calcium-containing ...

. This could be inferred from the absence of trapped glaze bubbles. If it is applied to an unfired body, the

calcium carbonate Calcium carbonate is a chemical compound with the chemical formula . It is a common substance found in Rock (geology), rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skel ...

will decompose, generating

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

, the releasing of which from the body to the glaze results in trapped bubbles in the glaze layers.

Current use and alternatives

Tin oxide has been widely used as the opacifier in sanitaryware glazes. In this application, additions of up to 6% are reported to be used. The cost of tin oxide rose considerably during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

(1914-1918), and resulted in a search for cheaper alternatives. The first successful replacement was

zirconia Zirconium dioxide (), sometimes known as zirconia (not to be confused with zirconium silicate or zircon), is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral ba ...

and later

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of th ...

. Whilst zirconium compounds are not as effective, their low price led to a gradual increase in popularity with an associated reduction in use of tin oxide. Today, tin oxide finds limited use in glazes, generally its use is restricted to specialist low temperature applications, and by artisanal studio potters.‘Ceramic Glazes.’ F.Singer & W.L.German. ''Borax Consolidated Limited''. London. 1960. The whiteness resulting from the use of zirconia has been described as more ''clinical'' than that from tin oxide, and is consequently preferred in some applications. The Koninklijke Tichelaar Makkum factory, or Royal Tichelaar Makkum, based in Makkum,

Friesland Friesland ( ; ; official ), historically and traditionally known as Frisia (), named after the Frisians, is a Provinces of the Netherlands, province of the Netherlands located in the country's northern part. It is situated west of Groningen (p ...

continue the production

using tin-glazed

The nature of tin glaze

Only one tin compound, tin(IV) oxide (SnO₂), also called stannic acid, is commercially exploited for tin glaze. After firing, tin oxide remains in suspension in the vitreous matrix of the glaze. Because tin's high refractive index is different from the vitreous matrix, light is scattered: hence the opacity of tin glaze. Generally speaking, the more different the

refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

between the particles and the glaze matrix, the larger the opacity. Similarly, the closer the particle size to the light wavelength (100–1000 nm for

visible light Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm ...

) and the more irregular the surface, the larger the degree of opacification. The degree of dissolution increases with the firing temperature, and hence the extent of opacity diminishes. Although dependent on the other constituents the solubility of tin oxide in glaze melts is generally low. Its solubility is increased by Na₂O, K₂O and B₂O₃, and reduced by

CaO Cao or CAO may refer to: Mythology *Cao (bull), a legendary bull in Meitei mythology Companies or organizations * Air China Cargo, ICAO airline designator CAO * CA Oradea, Romanian football club * CA Osasuna, Spanish football club * Canadian ...

, BaO, ZnO, Al₂O₃, and to a limited extent PbO. Some research on medieval tin glaze has shown that the particle size of tin oxide which appears as cassiterite is around several hundred nanometers, which corresponds to the range of wavelength of visible light.Molera, J., Pradell T., Salvadó, N. and Vendrell-Saz, M. "Evidence of Tin Oxide Recrystallization in Opacified Lead Glazes", ''Journal of American Ceramic Society'', 1999, 82:2871-2875 In some cases, the tin oxide is presented not only as small crystals but also as aggregates of particles. These factors – the high refractive index, the low solubility in glazes and the particle size make tin oxide an excellent opacifier. In the beginning of the use of tin oxide, it is mainly viewed as a slip layer between the glaze and ceramic body. This could be seen from the SEM photomicrographs of some earlier Islamic glazed ceramics, of which the particles of tin oxide are concentrated at the interface, together with the existence of

wollastonite Wollastonite is a calcium Silicate minerals, inosilicate mineral (calcium, Casilicon, Sioxygen, O3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or D ...

, diopside and air bubble as other opacifiers.Manson, R. B., and M. S. Tite, "The beginnings of tin-opacification of pottery glazes", ''Journal of Archaeological Science'' 39:41-58, 1997 The microanalysis of later tin glazes reveals the distribution of tin oxide through the glazes rather than just at the interface, which indicates that tin oxide is really acting as an opacifier instead of only a surface coating layer. Lead is usually brought into the glazes with tin oxide. The reaction between lead and tin oxide results in the recrystallisation of tin oxide, and thus enhances the degree of opacification in tin-opacified glazes than in tin-opacified glass. A high PbO/SnO₂ ratio is often found in ancient glazes. During the firing process,

lead oxide Lead oxides are a group of inorganic compounds with formulas including lead (Pb) and oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), gr ...

reacts with quartz at approximately 550 °C to form PbSiO₃, which then reacts with tin oxide to produce lead-tin oxide (PbSnO₃) at a temperature higher than 600 °C. After the formation of lead-tin oxide, the melting of PbSiO₃, PbO and PbSnO₃ occurs at the temperature in the range of 700 °C to 750 °C, resulting in the dissolution of PbSnO₃ to SnO₂. The degree of the crystallisation of SnO₂ increases with the increasing of temperature. During either heating or cooling, the recrystallisation is taken place until the supply of tin is exhausted. In the second heating, lead in the form of lead oxide no longer reacts with tin oxide to form lead silicate, thus the recrystallised

cassiterite Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite was the chief tin ore throughout ancient history and remains ...

(SnO₂) remain undissolved and precipitate in the glazes. The

nucleation In thermodynamics, nucleation is the first step in the formation of either a new Phase (matter), thermodynamic phase or Crystal structure, structure via self-assembly or self-organization within a substance or mixture. Nucleation is typically def ...

and growth rates of the precipitation depend upon temperature and time. The particle size of the cassiterite developed is also dependent on the temperature, and smaller than that used in the very beginning. It is the smaller particle size of the recrystallised SnO₂ in glazes that increases the opacity in tin-opacified glazes. Besides the increasing the opacity, the high lead oxide to tin oxide ratio also reduces the melting point of glazes, lead to a lower firing temperature during production.

The technology of tin-glazing

Analyses and recipes

The earliest

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

ern tin glazes used

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

and

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

compounds as fluxes in combination with the

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

in silica. An Islamic opaque white glaze has been analysed, and is quoted below as a Seger formula: ::*PbO=0.32 ::*CaO=0.32 ::*K₂O=0.03 ::*Na₂O=0.29 ::*MgO=0.04 ::*Al₂O₃=0.03 ::*SiO₂=1.73 ::*SnO₂=0.07 In this recipe, the addition of

alkali In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The a ...

helps to increase the hardness of the surface and clarify the colour of the glaze as well. With the development of tin glazes, the significant amount of tin oxide indicates its deliberate addition as an opacifier. A recipe involving the use of three ingredients was given in Abu’l-Qasim’s treatise from

Persia Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

in the 14th century: a glass- frit of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

and

potash Potash ( ) includes various mined and manufactured salts that contain potassium in water- soluble form.

, a lead-tin

calx Calx is a substance formed from an ore or mineral that has been heated. Calx, especially of a metal, is now understood to be an oxide. The term is also sometimes used in older texts on artists' techniques to mean calcium oxide. According to the ...

and a

calcination Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), generally f ...

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

and quartz. Afterwards, with the spread of tin glazes, lead gradually became the principal background in tin glazes, though a small proportion of alkali was still introduced in order to increase the fusibility. No specific recipes alluding to tin glazes in

have been found in ancient archives. However, recent research has shown that, at least since the 10th century AD, most Islamic white glazes in Spain were lead-silica glazes with tin oxide as an opacifier. That is, no alkaline glazes or lead-alkaline glazes have been found.Molera, J., M. Vendrell-Saz, and J. Pérez-Arantegui. 2001 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. A Seger analysis of a tin glaze from the early 20th century is: ::*PbO=0.52 ::*CaO=0.16 ::*K₂O=0.03 ::*Na₂O=0.29 ::*Al₂O₃=0.15 ::*SiO₂=2.77 ::*SnO₂=0.23 A more recent recipe is: ::*

Lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

bisilicate frit: 74% ::*

China clay Kaolinite ( ; also called kaolin) is a clay mineral, with the chemical composition aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4. It is a layered silicate mineral, with one tetrahedron, tetrahedral sheet of silica () linked through oxygen ...

: 10% ::* Whiting: 2% ::*

Flint Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start ...

, calcined: 4% ::* Tin oxide: 10% And another is: ::*Potassium

feldspar Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagiocl ...

: 65% ::*

Limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

: 11% ::*

Silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

: 11% ::*

Zinc oxide Zinc oxide is an inorganic compound with the Chemical formula, formula . It is a white powder which is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, Zinc metabolism, food supplements, rubbe ...

: 9% ::* Tin oxide: 4%

As a glaze colorant

In combination with chromium compounds addition of 0.5–1.5% tin oxide to a glaze result in a pink colour, with such glazes being known as Chrome-tin pinks. In conjunction with small additions of zinc oxide and titanium oxide, additions of tin oxide up to 18% to lead glazes can produce a satin or vellum surface finish. The firing temperatures of such glazes are low, in the region of 950–1000 °C because of the variable degrees of solution of the individual oxides. The amount of tin oxide used for coloured glazes depends upon the opacifying property of the chosen chromophore and the intensity of the colour desired; if a deep colour is required less opacifier will be needed than for pastel shades.’Ceramic Glazes’ C.W.Parmelee. ''Industrial Publications, Inc.'' Chicago. 1948.

References

Bibliography

*al-Saad, Z. 2002. Chemical composition and manufacturing technology of a collection of various types of Islamic glazes excavated from Jordan. Journal of Archaeological Science 29:803-810. *Allan, J. 1973. Abu'l-Qasim's treatise on ceramics. Iran 9:111-120. *Borgia, I., B. Brunettu, A. Sgamellontti, F. Shokouhi, P. Oliaiy, J. Rahighi, M. Lamehi-rachti, M. Mellini, and C. Viti. 2004. Characterisation of decorations on Iranian (10th–13th century) lustreware Applied Physics A 79 (257-261). *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) *Caiger-Smith, Alan, ''Lustre Pottery: Technique, Tradition and Innovation in Islam and the Western World'' (Faber and Faber, 1985) *Canby, S. R. 1997. "Islamic lustreware". In ''Pottery in the making: world ceramic traditions'', edited by I. Freestone and D. Gaimster. London: British Museum Press. *Coutts, Howard, ''The Art of Ceramics: European Ceramic Design, 1500–1830'', 2001, Yale University Press, , 9780300083873
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* [http://ceramicartsdaily.org/ceramic-glaze-recipes/low-fire-glaze-recipes/linda-arbuckles-majolica-glaze-recipe-cone-04-oxidation Low fire majolica glaze recipe cone 04 oxidation by Linda Arbuckle on http://ceramicartsdaily.org]
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