White lead is the basic lead carbonate 2PbCO₃·Pb(OH)₂. It is a complex

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

, containing both carbonate and hydroxide ions. White lead occurs naturally as a mineral, in which context it is known as hydrocerussite, a

hydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

cerussite Cerussite (also known as lead carbonate or white lead ore) is a mineral consisting of lead carbonate with the chemical formula PbCO3, and is an important ore of lead. The name is from the Latin ''cerussa'', white lead. ''Cerussa nativa'' was ...

. It was formerly used as an ingredient for

lead paint Lead paint or lead-based paint is paint containing lead. As pigment, lead(II) chromate (, "chrome yellow"), lead(II,IV) oxide, (, "red lead"), and lead(II) carbonate (, "white lead") are the most common forms.. Lead is added to paint to acceler ...

and a cosmetic called Venetian ceruse, because of its opacity and the satiny smooth mixture it made with dryable oils. However, it tended to cause

lead poisoning Lead poisoning, also known as plumbism and saturnism, is a type of metal poisoning caused by lead in the body. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertility, numbness and paresthesia, t ...

, and its use has been banned in most countries. Basic lead carbonate is produced by treating lead acetate with

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 ...

and air. In the laboratory procedure treats lead acetate with

urea Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest am ...

. It occurs naturally as the mineral

. The compound has been characterized by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

, which confirms the formula. The structure is complicated, features two kinds of Pb(II) sites, those bonded to hydroxide and those bonded to carbonate and hydroxide.

Related white lead compounds

White lead compounds known as lead soap were used as additive for lubricants for bearings and in machine shops. Lead soap was also used as an

oil drying agent An oil drying agent, also known as siccative, is a coordination compound that accelerates ( catalyzes) the hardening of drying oils, often as they are used in oil-based paints. This so-called "drying" (actually a chemical reaction that produces a ...

for paints made with

drying oil Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be conside ...

or air drying paints made with

alkyd resin An alkyd is a polyester resin modified by the addition of fatty acids and other components. Alkyds are derived from polyols and organic acids including dicarboxylic acids or carboxylic acid anhydride and triglyceride oils. The term ''alkyd'' is ...

s. Lead is often used with cobalt driers. Lead free substitutes have been developed to replace this use of lead in paint. A second basic lead carbonate is known with the formula .

History

What is commonly known today as the "Dutch method" for the preparation of white lead was described as early as Theophrastus of Eresos (ca. 300 BC), in his brief work on rocks or minerals, ''On Stones'' or ''History of Stones.'' His directions for the process were repeated throughout history by many authors of chemical and

alchemical Alchemy (from the Arabic word , ) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practised in China, India, the Muslim world, and Europe. In its Western form, alchemy is first ...

literature. The uses of cerussa were described as an external medication and pigment. Clifford Dyer Holley quotes from Theophrastus' ''History of Stones'' as follows, in his book ''The Lead and Zinc Pigments''. Later descriptions of the Dutch process involved casting metallic

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 ...

as thin buckles and corroded with

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...

in the presence of

. This was done by placing them over pots with a little

vinegar Vinegar () is an aqueous solution of diluted acetic acid and trace compounds that may include flavorings. Vinegar typically contains from 5% to 18% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting ...

(which contains acetic acid). These were stacked up and covered with a mixture of decaying dung and spent tanner's bark, which supplied the CO₂, and left for six to fourteen weeks, by which time the blue-grey lead had corroded to white lead. The pots were then taken to a separating table where scraping and pounding removed the white lead from the buckles. The powder was then dried and packed for shipment or shipped as a paste. One benefit of the process was that it was not necessary to dry the paste of white lead, removing its water. All that needed was to mill the paste with

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

, and the white lead would take up the oil and reject the residual water, to give white lead in oil.

Paints

White lead has been mostly supplanted in artistic use by titanium white, which has much higher tinting strength than white lead. Critics argue that substitutes like zinc oxide and titanium dioxide are more reactive, become brittle, and can flake off. The Smithsonian's Museum Conservation Institute exposes long-term problems with zinc white White lead is less used by today's painters, not because of its toxicity directly; but simply because its toxicity in other contexts has led to trade restrictions that make white lead difficult for artists to obtain in sufficient quantities.

Winsor & Newton Winsor & Newton (also abbreviated W&N) is an England, English manufacturing company based in London that produces a wide variety of fine art products, including acrylic paint, acrylics, oil paint, oils, watercolour painting, watercolour, gouache ...

, the English paint company, was restricted in 2014 from selling its flake white in tubes and now must sell exclusively in tins. In the eighteenth century, white lead paints were routinely used to repaint the hulls and floors of

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

vessels, to waterproof the timbers and limit infestation by

shipworm The shipworms, also called teredo worms or simply teredo (, via Latin ), are marine bivalve molluscs in the family Teredinidae, a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into (and commonly eventual ...

Other synonyms (as an art pigment)

Among the synonyms for white lead are Berlin white,

Cremnitz Kremnica (; , ) is a town in central Slovakia. It has around 5,300 inhabitants. The well-preserved medieval town built above important gold mines is the site of the oldest still-working mint in the world. Name The name is derived from Slovak ''k ...

white, Dutch white lead, flake white, Flemish white, Krems white, London white, Pigment White 1, Roman white, silver white, slate white and Vienna white.

References

External links

Lead white
Colourlex {{Authority control Lead(II) compounds Inorganic pigments Environmental impact of paint