Hobbies Fine Arts & Crafts Paint Pigments: Phthalo Blue (PB 15) A profile of phthalo blue paint pigment, including its characteristics. Share PINTEREST Email Print Paint Pigment: Phthalo Blue PB16. Image: ©2007 Marion Boddy-Evans. Licensed to About.com, Inc Fine Arts & Crafts Painting Basics Lessons & Tutorials Techniques Supplies Drawing & Sketching Arts & Crafts By Marion Boddy-Evans Marion Boddy-Evans is an artist living on the Isle of Skye, Scotland. She has written for art magazines blogs, edited how-to art titles, and co-authored travel books. our editorial process Marion Boddy-Evans Updated January 12, 2018 Characteristics: Phthalo blue is a bright, intense blue that's very dark when used thickly. Used as a thin glaze it's very transparent. Mixed with white it's an opaque, beautiful sky blue. Phthalo blue is available in green and red shades. Common Names: Thalo blue, monestial blue, Winsor blue, monastral blue, phthalocyanine blue, heliogen blue, intense blue, Old Holland blue, Rembrandt blue. Color Index Name: PB 15. PB15.6 (green shade). PB 16 (metal-free).(Color Index Explained) Color Index Number: 74100. 74160. Pigment Origin: Copper phthalocyanine, a synthetic organic pigment. Used for Painting Since: 1930s. (Invented in 1928.) Opacity/Transparency: Transparent. Tinting Ability: Strong.(Tinting explained) Lightfastness Rating: ASTM I.(Lightfastness explained) Oil Paint Drying Speed: Slowish. Specific Notes: Sometimes used as a cheaper alternative for cerulean blue. Quotes About This Pigment:"Prized for its mixing abilities, it [phthalo blue] has also become the basis of many student-range blues as it can be reduced considerably and still offer a strong color." -- Simon Jennings, Artist's Color Manual, p14."As a blue pigment, [phthalo blue] shares none of the luxuriant hue of ultramarine; but its importance lies more in the fact that it absorbs red and yellow almost totally, while transmitting or reflecting blue and green." -- Philip Ball, Bright Earth, p279.