Smalt
Encyclopedia
Smalt is powdered glass
, colored to a deep powder blue
hue using cobalt
ions derived from cobalt oxide (see cobalt glass
for the non-powdered glass). Smalt is used as a pigment
in painting, and for surface decoration of other types of glass and ceramics, and other media. Cobalt aluminate can be used in a similar way, and is now more common, often known as "cobalt blue
".
region, and this is the pigment normally known as smalt. In paintings, smalt has a tendency to lose its colour over a long period and is little used today. However used in ceramics for underglaze
decoration it keeps its colour well, and is the main blue used in blue and white pottery from a wide range of dates and areas, including Chinese blue and white porcelain from the Yuan
and Ming dynasties
, Renaissance Italian maiolica
and Delftware
.
Chinese porcelain
used smalt glazes from the Tang Dynasty
onwards, though Chinese cobalt glass is found from the Chou dynasty (1122-221 BC). Cobalt was used as a pigment in Central Asia
from the 13th century. A fragment of a mud painting in the ancient Tangut city of Khara-Khoto
has been found to contain smalt, judged to be dated between 11th to 13th century. A large quantity of smalt was purchased for the decoration of the gallery of François Ier
at Fontainebleau
in 1536. Smalt, normally now discoloured, is common in European paintings from the 15th to 17th centuries. for example, it was found in Hans Holbein the Younger's portrait of Sir William Butts (ca. 1540), in Michael Pacher's painting "The Early Fathers' Altar" (ca. 1483), and in the frescos of Domenico Ghirlandaio (1449–1494).
The invention of a European smalt process is sometimes credited to a Bohemia
n glass
maker named Christoph Schurer, around 1540-1560 The process used for producing cobalt smalt glass at the Blaafarveværket
industrial manufacturing center in Norway in the 19th century has been documented as smelting cobalt oxide together with quartz and potassium carbonate. The result was an intensive blue glass-like substance that was ground and sold to producers of glassware and porcelain.
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
, colored to a deep powder blue
Powder blue
Powder blue may refer to two different colors.The paler variant is often associated with powder snow.-Powder blue :The web color powder blue is shown on the right....
hue using cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
ions derived from cobalt oxide (see cobalt glass
Cobalt glass
Cobalt glass is a deep blue colored glass prepared by adding cobalt compounds to the molten glass. It is appreciated for its attractive color. It is also used as an optical filter in flame tests to filter out the yellow flame caused by the contamination of sodium, and expand the ability to see...
for the non-powdered glass). Smalt is used as a pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
in painting, and for surface decoration of other types of glass and ceramics, and other media. Cobalt aluminate can be used in a similar way, and is now more common, often known as "cobalt blue
Cobalt blue
Cobalt blue is a cool, slightly desaturated blue color, historically made using cobalt salts of alumina. It is used in certain ceramics and painting; the different cobalt pigment smalt, based on silica, is more often used directly in tinted transparent glasses...
".
History
The earliest known example of cobalt aluminate glass dates to a lump from about 2000BC in ancient Mesopotamia, very possibly intended for use as a pigment; it is then rare until the modern era. About five centuries later cobalt oxide smalt appears as a pigment in Egyptian pottery, and soon after in the AegeanAegean Sea
The Aegean Sea[p] is an elongated embayment of the Mediterranean Sea located between the southern Balkan and Anatolian peninsulas, i.e., between the mainlands of Greece and Turkey. In the north, it is connected to the Marmara Sea and Black Sea by the Dardanelles and Bosporus...
region, and this is the pigment normally known as smalt. In paintings, smalt has a tendency to lose its colour over a long period and is little used today. However used in ceramics for underglaze
Underglaze
Underglaze is a method of decorating ceramic articles, the decoration is applied to the surface before it is glazed. Because the glaze will subsequently cover it such decoration is completely durable, but because the subsequent glost firing is at a higher temperature than used in on-glaze...
decoration it keeps its colour well, and is the main blue used in blue and white pottery from a wide range of dates and areas, including Chinese blue and white porcelain from the Yuan
Yuan Dynasty
The Yuan Dynasty , or Great Yuan Empire was a ruling dynasty founded by the Mongol leader Kublai Khan, who ruled most of present-day China, all of modern Mongolia and its surrounding areas, lasting officially from 1271 to 1368. It is considered both as a division of the Mongol Empire and as an...
and Ming dynasties
Ming Dynasty
The Ming Dynasty, also Empire of the Great Ming, was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history", was the last dynasty in China ruled by ethnic...
, Renaissance Italian maiolica
Maiolica
Maiolica is Italian tin-glazed pottery dating from the Renaissance. It is decorated in bright colours on a white background, frequently depicting historical and legendary scenes.-Name:...
and Delftware
Delftware
Delftware, or Delft pottery, denotes blue and white pottery made in and around Delft in the Netherlands and the tin-glazed pottery made in the Netherlands from the 16th century....
.
Chinese porcelain
Chinese porcelain
Chinese ceramic ware shows a continuous development since the pre-dynastic periods, and is one of the most significant forms of Chinese art. China is richly endowed with the raw materials needed for making ceramics. The first types of ceramics were made during the Palaeolithic era...
used smalt glazes from the Tang Dynasty
Tang Dynasty
The Tang Dynasty was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire...
onwards, though Chinese cobalt glass is found from the Chou dynasty (1122-221 BC). Cobalt was used as a pigment in Central Asia
Central Asia
Central Asia is a core region of the Asian continent from the Caspian Sea in the west, China in the east, Afghanistan in the south, and Russia in the north...
from the 13th century. A fragment of a mud painting in the ancient Tangut city of Khara-Khoto
Khara-Khoto
Khara-Khoto was a Tangut city in the Ejin khoshuu of Alxa League, in western Inner Mongolia, near the former Gashun Lake. It has been identified as the city of Etzina, which appears in The Travels of Marco Polo.-History:...
has been found to contain smalt, judged to be dated between 11th to 13th century. A large quantity of smalt was purchased for the decoration of the gallery of François Ier
Francis I of France
Francis I was King of France from 1515 until his death. During his reign, huge cultural changes took place in France and he has been called France's original Renaissance monarch...
at Fontainebleau
Fontainebleau
Fontainebleau is a commune in the metropolitan area of Paris, France. It is located south-southeast of the centre of Paris. Fontainebleau is a sub-prefecture of the Seine-et-Marne department, and it is the seat of the arrondissement of Fontainebleau...
in 1536. Smalt, normally now discoloured, is common in European paintings from the 15th to 17th centuries. for example, it was found in Hans Holbein the Younger's portrait of Sir William Butts (ca. 1540), in Michael Pacher's painting "The Early Fathers' Altar" (ca. 1483), and in the frescos of Domenico Ghirlandaio (1449–1494).
The invention of a European smalt process is sometimes credited to a Bohemia
Bohemia
Bohemia is a historical region in central Europe, occupying the western two-thirds of the traditional Czech Lands. It is located in the contemporary Czech Republic with its capital in Prague...
n glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
maker named Christoph Schurer, around 1540-1560 The process used for producing cobalt smalt glass at the Blaafarveværket
Blaafarveværket
Blaafarveværket in Modum, Norway, founded by King Christian VII of Denmark-Norway in the 1770s, became the largest industrial company of the country in the mid-19th century. The works mined cobalt ore and manufactured by smelting blue cobalt glass and cobalt blue pigment...
industrial manufacturing center in Norway in the 19th century has been documented as smelting cobalt oxide together with quartz and potassium carbonate. The result was an intensive blue glass-like substance that was ground and sold to producers of glassware and porcelain.
Further reading
Smalt, Bruno Mühlethaler and Jean Thissen, Studies in Conservation, Vol. 14, No. 2 (May, 1969), pp. 47–61, JSTORExternal links
- Smalt Pigments through the Ages