M. Graham Artists’ Gouache Color 15ml tubes (OPEN STOCK) (Phthalocyanine Blue 140)

Phthalo Blue PB15:3 is a structural variant of Phthalo Blue PB15 that produces more greenish tones. Developed by chemists using the trade name Monastral Blue, the organic blue dyestuff now known as Phthalo Blue was presented as a pigment in November 1935 in London. Its discovery was accidental. The dark color 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 a cyan to replace Prussian Blue.