Lead(II) oxide in the context of "Lead-glazed earthenware"

Play Trivia Questions online!

or

Skip to study material about Lead(II) oxide in the context of "Lead-glazed earthenware"

Ad spacer

⭐ Core Definition: Lead(II) oxide

Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula PbO. It occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components.

↓ Menu

>>>PUT SHARE BUTTONS HERE<<<

👉 Lead(II) oxide in the context of Lead-glazed earthenware

Lead-glazed earthenware is one of the traditional types of earthenware with a ceramic glaze, which coats the ceramic bisque body and renders it impervious to liquids, as terracotta itself is not. Plain lead glaze is shiny and transparent after firing. Coloured lead glazes are shiny and either translucent or opaque after firing. Three other traditional techniques are tin-glazed (in fact this is lead glaze with a small amount of tin added), which coats the ware with an opaque white glaze suited for overglaze brush-painted colored enamel designs; salt glaze pottery, also often stoneware; and the feldspathic glazes of Asian porcelain. Modern materials technology has invented new glazes that do not fall into these traditional categories.

In lead glazes, tints provided by impurities render greenish to brownish casts, with aesthetic possibilities that are not easily controlled in the kiln. The Romans used lead glazes for high-quality oil lamps and drinking cups. At the same time in China, green-glazed pottery dating back to the Han period (25–220 AD) gave rise eventually to the sancai ('three-color') Tang dynasty ceramics, where the white clay body was coated with coloured glazes and fired at a temperature of 800 degrees C. Lead oxide was the principal flux in the glaze. Polychrome effects (i.e. the colours) were obtained by using the oxides of copper (which turns green), iron (brownish yellow), and less often manganese (brown) and cobalt (blue).

↓ Explore More Topics
In this Dossier

Lead(II) oxide in the context of İznik pottery

Iznik pottery, or Iznik ware, named after the town of İznik in Anatolia where it was made, is a decorated ceramic that was produced from the last quarter of the 15th century until the end of the 17th century. The Ottoman Turkish motivation for creating İznik ware was to imitate the prestige and symbolic value of Chinese porcelain, not its specific decorative designs. While their conceptual origin lies in Chinese blue-and-white porcelain, their decorative design is a distinct Ottoman adaptation of the International Timurid style. This adaptation is marked by a transformation from the prototype's languid quality to a more forceful and contained design, distinguished by its intensity and three-dimensional feel. Technologically, these wares are unique, differing from the methods used for contemporary Iranian pottery and Ottoman architectural tilework. This distinct manufacturing process is thought to be an invention of Anatolian potters.

İznik was an established centre for the production of simple earthenware pottery with an underglaze decoration when, in the last quarter of the 15th century, craftsmen in the town began to manufacture high quality pottery with a fritware body painted with cobalt blue under a colourless transparent lead glaze. The change was almost certainly a result of active intervention and patronage by the recently established Ottoman court in Istanbul who greatly valued Chinese blue-and-white porcelain.

↑ Return to Menu

Lead(II) oxide in the context of Litharge

Litharge (from Greek lithargyros, lithos 'stone' + argyros 'silver' λιθάργυρος) is one of the natural mineral forms of lead(II) oxide, PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It forms as coatings and encrustations with internal tetragonal crystal structure. It is dimorphous with the yellow orthorhombic form massicot. It forms soft (Mohs hardness of 2), red, greasy-appearing crusts with a very high specific gravity of 9.14–9.35. PbO may be prepared by heating lead metal in air at approximately 600 °C (lead melts at only 300 °C). At this temperature it is also the end product of heating of other lead oxides in air. This is often done with a set of bellows pumping air over molten lead and causing the oxidized product to slip or fall off the top into a receptacle, where it quickly solidifies in minute scales.

↑ Return to Menu

Lead(II) oxide in the context of Massicot

Massicot is lead (II) oxide mineral with an orthorhombic lattice structure.Lead(II) oxide (formula: PbO) can occur in one of two lattice formats, orthorhombic and tetragonal. The red tetragonal form is called litharge. PbO can be changed from massicot to litharge (or vice versa) by controlled heating and cooling. At room temperature massicot forms soft (Mohs hardness of 2) yellow to reddish-yellow, earthy, scaley masses which are very dense, with a specific gravity of 9.64. Massicot can be found as a natural mineral, though it is only found in minor quantities. In bygone centuries it was mined. Nowadays massicot arises during industrial processing of lead and lead oxides, especially in the glass industry, which is the biggest user of PbO.

The definition of massicot as orthorhombic PbO dates from the 1840s, but the substance massicot and the name massicot has been in use since the late medieval era. There is some evidence that the ancient Romans used the substance.

↑ Return to Menu

Lead(II) oxide in the context of Lead glass

Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass typically contains 18–40% (by mass) lead(II) oxide (PbO); modern lead crystal or leaded crystal, historically also known as flint glass for the original silica source, contains a minimum of 24% PbO. Lead glass is desirable for a variety of uses due to its clarity. In marketing terms it is often called crystal glass.

The term lead crystal is, technically, not an accurate way to describe lead glass, because glass lacks a crystalline structure and is instead an amorphous solid. The use of the term remains popular for historical and commercial reasons but is sometimes changed to simply crystal because of lead's reputation as a toxic substance. It is retained from the Venetian word cristallo to describe the rock crystal (quartz) imitated by Murano glassmakers. This naming convention has been maintained to the present day to describe decorative holloware.

↑ Return to Menu

Lead(II) oxide in the context of Tetraethyl lead

Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula Pb(C2H5)4. It was widely used as a fuel additive for much of the 20th century, first being mixed with gasoline beginning in the 1920s. This "leaded gasoline" had an increased octane rating that allowed engine compression to be raised substantially and in turn increased vehicle performance and fuel economy. TEL was first synthesized by German chemist Carl Jacob Löwig in 1853. American chemical engineer Thomas Midgley Jr., who was working for the U.S. corporation General Motors, was the first to discover its effectiveness as an knock inhibitor on December 9, 1921, after spending six years attempting to find an additive that was both highly effective and inexpensive.

Of the some 33,000 substances in total screened, lead was found to be the most effective antiknock agent, in that it necessitated the smallest concentrations necessary; a treatment of 1 part TEL to 1300 parts gasoline by weight is sufficient to suppress detonation. The four ethyl groups in the compound served to dissolve the active lead atom within the fuel. When injected into the combustion chamber, tetraethyllead decomposed upon heating into ethyl radicals, lead, and lead oxide. The lead oxide scavenges radicals and therefore inhibits a flame from developing until full compression has been achieved, allowing the optimal timing of ignition, as well as the lowering of fuel consumption. Throughout the sixty year period from 1926 to 1985, an estimated 20 trillion liters of leaded gasoline at an average lead concentration of 0.4 g/L were produced and sold in the United States alone, or an equivalent of 8 million tons of inorganic lead, three quarters of which would have been emitted in the form of lead chloride and lead bromide. Estimating a similar amount of lead to have come from other countries' emissions, a total of more than 15 million tonnes of lead may have been released into the atmosphere.

↑ Return to Menu

Lead(II) oxide in the context of Ceramic flux

Fluxes are substances, usually oxides, used in glasses, glazes and ceramic bodies to lower the high melting point of the main glass forming constituents, usually silica and alumina. A ceramic flux functions by promoting partial or complete liquefaction. The most commonly used fluxing oxides in a ceramic glaze contain lead, sodium, potassium, lithium, calcium, magnesium, barium, zinc, strontium, and manganese. These are introduced to the raw glaze as compounds, for example lead as lead oxide. Boron is considered by many to be a glass former rather than a flux.

Some oxides, such as calcium oxide, flux significantly only at high temperature. Lead oxide is the traditional low temperature flux used for crystal glass, but it is now avoided because it is toxic even in small quantities. It is being replaced by other substances, especially boron and zinc oxides.

↑ Return to Menu