Every year, oil paint manufacturer Gamblin holds a Torrit Grey Competition. Torrit Grey is a color made from all the pigment throughout the year that's sucked into the company's air filtration system. The result is a grey that varies from year to year, sometimes cool, sometimes warm, which is distributed to art suppliers for their customers to try. A competition is held every October in honor of Earth Day and the lucky winners get gift certificates for Gamblin paints, solvents, and mediums.
Only 3 colors can be used in the paintings: Torrit Grey, black and white.

Here are my entries:

"All for Naught"   20" x 16"  

  Torrit with Fast Matte Chromatic Black and Titanium White

Medium: Galkyd Lite

"Apple Pi"   10" x 10"
Torrit with Ivory Black and Titanium White
Medium: Galkyd Lite