What are the origins and meanings of Quinacridone and Phthalo?

Quinacridones are a very important group of pigments which originated in the 1950's.  The first quinacridones were introduced by Winsor & Newton as Permanent Rose and Permanent Magenta.  With their highly transparent and lightfast hues, these colours transformed the pink and mauve section of the palette, an area that had always suffered from poor lightfastness.  Over the next 50 years many more colours became available, ranging from deep crimson to gold.  These are achieved by different combinations of the chemicals involved.

Phthalo Blue is simply an abbreviation of phthalocyanine blue and is made from copper phthalocyanine (colour index pigment blue 15.) This pigment is available in several slightly different hues , varying slightly in colour, but all covered by the generic name “phthalo blue”. This is the only pigment in Cotman Intense Blue.

Winsor and Newton also sell slightly different hues of phthalo blue in their Artists’ Water Colour range such as Winsor Blue Red Shade and Winsor Blue Green Shade. Once again, the only pigment used is phthalo blue.

Similarly, phthalocyanine green is available in two basic hues, a yellow shade (pigment green 36) which we sell as Intense Green in Cotman Water Colour and Winsor Green Yellow Shade in Artists’ Water Colour  and a bluer shade (pigment green 7), sold as Viridian Hue in Cotman Water Colour and Winsor Green Blue Shade in Artists’ Water Colour.

In all cases the only pigment is phthalo green, but the blue shade was the original and is more commonly referred to as “phthalo green”.