Chromium Green Oxide is a warm mid green color well liked by artists. It is one of the top 2 or 3 pigments as far as lightfastness goes. It is very much a French color. The element chromium was discovered by Louis Nicolas Vauquelin in 1797 which lead to his identification of Chromium Green Oxide in 1807 but was not until 1838 when a practical process for making the pigment was developed by Parisian color maker Pannetier who kept his methods secret. In 1859 another French chemist named Guignet patented a method for making viridian which is chemically identical to Chromium Green Oxide with the exception that an extra step is taken in which the pigment is hydrated and ends up with two water molecules attached to the oxide of chromium. This turns the color from an opaque yellowish mid green to a darker, transparent, blue green. Viridian was a beautiful color and overshadowed its duller cousin. In the modern world where Phthalo Green has largely replaced the use of the original Viridian pigment, the older mid green Chromium Green Oxide has kept going with undiminished popularity.
Chemical Description: Anhydrous chromium sesquioxide
Pigment Numbers: PG17
Lightfastness Rating: ASTM I
Pigment Opacity: Opaque
Paint Opacity: Opaque