D097 Sky Blue/Bleu Cíel - Phthalo Blue PB15 (organic copper Phthalocyanine)

Developed by chemists using the trade name Monastral Blue, the organic blue dyestuff is now known as Phthalo Blue, was presented as a pigment in November 1935 in London. Its discovery was accidental. The dark colour was observed in a kettle where a dye was being made from a British dyestuff plant. The demand for such a pigment came from commercial printers who wanted cyan to replace Prussian Blue.

Series: A

Lightfast: ***

Pigments Name: PB15 Phthalo Blue

Pigment Type: Organic

Chemical Name: Copper phthalocyanine

Properties: Phthalo Blues are pure and clean primary blues with superior covering power. They have a very high tinting strength and tend to overwhelm other pigments, but if colour strength can be controlled, they make predictable mixed colours. In oil form, blues are intense and slow drying. When mixed with other colours or if chlorine is added, Phthalo Blue quickly tends towards green. When using alone, mix with some white, as Phthalo Blue can be semi-transparent and almost black on its own. It is among the most compatible of modern colours with mineral colours and is considered more reliable than Prussian Blue while sharing the same physical and colour properties. Phthalo Blue is a good colour for glazing.

Permanence: Phthalo Blues are completely lightfast and stable and are permanent for all paint uses. They are currently used in inks, coatings, and many plastics due to their stability and are considered a standard pigment in printing ink and the packaging industry.

Toxicity: Phthalo Blues have no significant hazards, although those made before 1982 contained some PCBs (polychlorinated biphenyls).

Alternate Names: Bocour Blue, Cyan Blue, Helio Blue, Heliogen Blue, Intense Blue, Monastral Blue, Phthalocyanine Blue, Rembrandt Blue, Thalo Blue, Winsor Blue.