Aureolin has an unusual quality – when applied thinly or watered down to a watercolor-like wash the full beauty of the pigment is revealed in its under-tone. The watercolorist is only interested in that bright clean under-tone but the acrylic painter has the choice of utilizing the mass-tone/under-tone (the full strength surface colour of a pigment viewed by reflective light is called its mass or top tone, its colour effect when it is spread out thinly is called undertone) differences for some very beautiful effects.
Chemical Description: Potassium cobalt nitrite
Pigment Number: PY40
Lightfastness Rating: BWS8
Pigment Opacity: Semi-Transparent
Paint Opacity: Transparent