Lead tetroxide

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Red lead at 500x transmitted light

Description

Red lead at 500x polarized light

A heavy, bright red powder that occurs naturally as the mineral Minium. The mineral form, however, was rarely used. Instead lead tetroxide was prepared by slowly heating lead monoxide in a furnace with a constant flow of air. Excess heating will turn the pigment to an orange shade that is known as Orange mineral. Lead tetroxide, also called Red lead oxide, was one of the earliest synthetic pigments. It is no longer used as an artists color because is has poor light stability and poor working properties. Instead, red lead is used to color glass, enamels, and ceramic glazes. It is also used as a flux in porcelain painting, an anticorrosive paint for iron and steel, and as a component in lead batteries. Because of its toxicity, the use of red lead is declining.

Synonyms and Related Terms

red lead; Pigment Red 105; CI 77578; mønje (Dan.); minio (Esp.); tetróxido de chumbo (Port.); minium (Fr.); lead oxide red; lead tetraoxide; orange mineral; Saturn red; Paris red; minio; burnt white lead; red oxide of lead; plumbous plumbate; lead orthoplumbate; mineral red

Chemical structure

Lead tetroxide.jpg


Risks

  • Toxic by inhalation or ingestion.
  • Skin contact may cause irritation or ulcers.
  • Carcinogen, teratogen, suspected mutagen.
  • Discolored by hydrogen sulfide.
  • ThermoFisher: SDS

Physical and Chemical Properties

Soluble in glacial acetic acid, hot HCl, nitric acid with peroxide present. Insoluble in water and ethanol.

Composition Pb3O4
CAS 1314-41-6
Density 8.32-9.16 g/ml
Molecular Weight mol. wt. = 685.6
Refractive Index 2.42

Resources and Citations

  • E. West-Fitzhugh, "Red Lead and Minium", Artists Pigments, Volume 1, R. Feller (ed.), Cambridge University Press: Cambridge, 1986.
  • R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966 Comment: density = 8.73 and ref. index = 2.42
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 5449
  • Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979