Phthalocyanine Blue Lake is it's full name, a chlorinated copper invented in 1935, this was one of the first synthetic organic pigments to be accepted as reliably permanent. It is sometimes seen as a modern replacement for Prussian blue, but its unmixed colour is slightly more cyan, and in hues it exhibits a unique range of throbbing, intense, greenish blues which are quite distinct from the latter.
Having the most powerful tint power of any colour in the Michael Harding range, this paint will blow any mix apart; if you wish to avoid doing so, add it in tiny quantities and with caution! Its ferrous content makes it a great drier, and like Prussian Blue it shows a tendency to bronze on drying.
Fast Drying. Transparent. Excellent Lightfastness. High Oil Content.