Color Curriculum

Phthalocyanine (Phthalo Pigments)

By Carolyn Payzant

Originally appeared in The Botanical Artist – Volume 14, Issue 1

 

I had a request to share what I know about one of the most challenging pigments that a watercolor artist can use, phthalo pigments. Remember those pigment numbers on the side of a tube of paint and how I have stressed how important they are? This is never more important than when using any phthalo blue or green pigments.  

All PB15:1 and PB15:6 are phthalo blue with a red bias. This bias can be slight to intense. (Most experts consider a slight red bias to be the middle of the blue spectrum.) All PB15:3 are phthalo blue with a green bias. A few PB15:3 pigments flocculate. (I prefer PB16 as my Phthalo Blue with a green bias.) If you want to purchase only one of the above I would suggest Daniel Smith’s Phthalo Blue RS or M. Graham’s Phthalocyanine Blue. Either will be pleasing when mixed with red or green biased pigments. If you want to purchase both biases in this pigment I would suggest Winsor Blue RS and Winsor Blue GS, as they give the widest spread and the strongest bias. I don’t have either the phthalo blue with a red bias or blue bias on my palette as I prefer to use French ultramarine blue as my blue with a red bias – it’s not quite as staining and is very transparent (See my article of December 2007, Daniel Smith’s PB29 French Ultramarine Blue.)  

All PB16 are phthalo turquoise. I love this pigment and use it as my blue with a strong green bias. (See my article of June 2007, Holbein’s PB16 Marine Blue.)  

The phthalo greens are easier to navigate.  

All PG7 are phthalo green with a blue bias. This pigment is the workhorse of the industry. Your tubes of paint that have beautiful crafted marketing names (convenient greens) such as: green blue, transparent turquoise, phthalo turquoise, emerald green, olive green and most of the Hooker’s greens, permanent greens and sap greens are generally made from PG7 giving you instant gratification. My favorite PG7 is Maimeriblu’s Cupric Green Deep.  

All PG 36 are phthalo green with a yellow bias, less of a workhorse than PG7 but with that being said some Hooker’s greens, permanent greens, and sap greens are made from PG36. My favorite PG36 us Maimeriblu’s Cupric Green Light. I find Maimeriblu’s Cupric Greens extremely useful in tweaking yellow and blue pigments. I seldom use them on their own.  

If you are using any convenient green, please, please check the lightfastness of the yellow that the manufacturer has used in their formulation. Let me say this again: check the lightfastness of the yellow that the manufacturer has used. Do I use any convenient green? Of course. I love DS Cascade Green. It flocculates giving multi- dimensional elements to the color. Most convenient greens are mixed so thoroughly that little of their individual components are visible unless they flocculate.  

Attributes of Phthalo Pigments  

All of the phthalo pigments are highly staining, transparent to semi-transparent, little to no granulation, most blossom, mix well with other pigments, and have a huge drying shift. Drying shift means the change of color as the paint dries, almost always lighter. Bruce MacEvory’s research – see www.handprint.com – reveals that the drying shift of phthalo blue with a red bias shifts 46% and the green bias shifts 26%.  On the other hand his research shows phthalo green has less of a drying shift (but still rather large) with the blue bias shifting 15-20% and the yellow bias 20%.

First time users beware and handle with care. Practice, practice, practice, is all I can recommend.