Prussian blue, and ultramarine, each iteration has opened new realms of expression. Artists have long been drawn to its depths, from Picasso’s Blue Period to Yves Klein’s iconic Klein Blue ...

and examine the ash. BLUE COLORS.—These may consist of indigo, logwood, prussian blue or ultramarine. Indigo blue is fixed on cloth in various ways,—1st, in the blue vat; 2nd, as so-called ...