Artists paints suffered for thousands of years because of the fugitive nature of most red colors available in earlier years. Or they were highly poisonous. We are very fortunate to live in an age when we have the quinacridones. Not only are they non-toxic, they are highly permanent (comparable to the Cadmium Red in that regard) and provide the much needed blue-reds that the pyrroles cannot provide. This particular shade of Quinacridone Red is one of the first red variants developed from what was originally a more violet quinacridone (no, Matisse did not make a mistake when they list the pigment information as PV19) and is particularly transparent. if opacity is required then reach for the Cadmium Red but transparency is required. The artist may be using a glazing technique, or looking for that jewel-like fire in a color from the light traveling through the color. If that is what is needed then put the Cadmium Red back and reach for the tube of Quinacridone Red.
Chemical Description: Quinacridone
Pigment Number: PV19
Lightfastness Rating: ASTM I
Pigment Opacity: Semi-Transparent
Paint Opacity: Transparent