This month we continue our “Pigment of the Month” series, detailing the origins, history, and eventual discontinuation of pigments once common on the artists’ palette. In this next installment, we explore the history of Emerald Green, and the chemical composition that made it both brilliant and lethal.
An artificial pigment, Emerald Green is chemical compound Copper(II)-acetoarsenite. It was developed at the beginning of the 19th century by Russ and Sattler in Schweinfurt, Germany, and was made commercially available in 1814. The goal with the formulation of Emerald Green was to improve upon Scheele's Green, which had a tendency to blacken when exposed to sulfides. However, thought Emerald Green was considered brilliant in color and more durable than Scheele's, it also had the same tendency to blacken when exposed to sulfides. For fine artists, this was a particularly difficult issue when using other paints that contained sulfur, such as cadmium yellow. Artists would attempt to isolate the Emerald Green with varnish, preventing contact with other pigments in an effort to minimize the discoloration -- but this was the least of Emerald Green’s problems.
The chemical formula that provided the brilliant color of Emerald Green contained arsenic, making the pigment highly toxic. As it was also low-cost to produce, the pigment was used not only for artist’s paints, but larger applications like household paints, wallpapers, and fabric dyes. With such widespread use, Emerald Green left its mark on history though the arsenic poisoning suffered by those unfortunate enough to experience long-term or high-levels of exposure. The highly toxic nature of Emerald Green did lead to manufacturers ceasing production of the original chemical formula, though this did not happen until as late as the mid 20th century. However, by the turn of the 20th century, Cobalt Green had grown in popularity and availability, making Emerald Green obsolete.
“A History of Pigment Use in Western Art Part 2” http://www.pcimag.com/
“Emerald green” http://www.webexhibits.org/
“Emerald Green” http://colourlex.com
“Spotlight on Colour: Emerald Green” http://www.winsornewton.com/
Zieske, Faith. “An Investigation of Paul Cézanne's Watercolors With Emphasis on Emerald Green” The Book and Paper Group Annual. 14 (1995) The American Institute for Conservation http://cool.conservation-us.org/