Prussian Blue: First synthetic color of the Industrial Revolution discovered by accident in 1704 while a chemist was trying to formulate artificial crimson. Warm blue with more muted tint than Phthalo Blue. It has a high tinting strength is lightfast and is especially beautiful in its transparency.Pigment: Ferri-ammonium ferrocyanide (PB 27:1)Vehicle: Burnt Plate OilSeries 2 SEMI-TRANSPARENT