Turning oil paint into a gel helped 19th-century painters finish masterpieces faster

It used to be that artists working with oil paint needed to wait weeks—sometimes even months—for a paint layer to dry before they could apply strokes of a new color to the canvas. There’s a reason the saying “watching paint dry” became synonymous with boredom. Then in the 19th century, artists such as J. M. W. Turner began following a “gumtion” recipe to formulate their paints. The change gave paint a jellylike viscosity that made it possible for artists to complete an oil artwork in only days. A team of researchers led by Laurence de Viguerie and Philippe Walter of the University of Pierre & Marie Curie have now taken advantage of modern spectroscopy to uncover the chemistry behind the paint recipes that Turner and other artists used (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201611136). The team recreated the gumtion formulation by adding lead acetate to a common oil paint base of mastic resin, linseed oil, and turpentine. They found that the paint gelled similarly to how traditional oil paint dries via an oxidative free-radical mechanism. But the presence of the lead acetate quickened the process. The metal ions didn’t just increase the rate of drying, they also integrated into the gel’s molecular architecture. The researchers say the technological advance revolutionized the ability of artists “to express sensations or feelings, capturing momentary effects of light” using more fluid, spontaneous, and loose brushwork.