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Artists’ oil paints contain inorganic pigments mixed into an organic linseed oil binder. Linseed oil (an ester of glycerol with linoleic, oleic, and linolenic fatty acids) “dries” by creating crosslinks between molecules. These crosslinks are formed when the double bonds in the organic fatty acids open up and reconnect with adjacent molecules. This forms a film or skin that seals in the inorganic pigments, many of which are toxic. Light is needed for this slow polymerization reaction to occur. The thinner the layer of linseed oil, the faster the oil paint dries because the crosslinks occur more quickly.

Concepts

  • Density
  • Solubility
  • Surface Tension
  • Organic Chemistry