Phthalocyanine Blue
PB15:6
Alternate Name
Phthalo Blue Green Shade
Pigment Description
Rare but sometimes found in artist paints. General information can be found in the entry for PB15 as well as the in-depth article on Phthalo blues. This is the "e form" of pigment 74160.
In terms of health and safety, these pigments contain copper. Please see the Artist's Guide to Health and Safety for information about the hazards associated with copper pigments. The author's most recent updated writing can be found through her site. See also the note at the bottom of this section on dioxins and PCBs.
Phthalo Blue requires a moderate amount of oil. Opinion is divided on its drying time with some saying medium to slow and others listing it as fast. It seems to frequently contain additives, stabilizers, and extenders. This may have less lightfastness (ASTM II) in watercolors. While phthalos are thought to be less toxic than other some paints, avoid tubes made before 1982 (or even we have heard as late as 1986) as they may be contaminated with impurities such as PCBs. Handle all artist colors with care.
Resources
PB15:6 pigment data from David G. Myers, The Color of Art Pigment Database, Artiscreation.com
Elliott, Virgil. Traditional Oil Painting. Echo Point Books & Media, LLC, 2019. https://amzn.to/4nwIdzq,
Spurgeon, Tad. Living Craft: A Painter's Process. Mt. Airy, Philadelphia, PA: Zoetrope, 2018. Newer version available here: https://www.thomaskitts.com/page/36804/tad-spurgeons-living-craft,
Information about PB15:6 from Bruce MacEvoy, Handprint Guide to Watercolors, General information about this class of pigments from Handprint
CAMEO Materials Database: Conservation & Art Materials Encyclopedia Online, Museum of Fine Arts Boston. (Accessed June 2025). Phthalocyanine Blue https://cameo.mfa.org/wiki/Phthalocyanine_blue. Museum of Fine Arts Boston.
Read an in-depth article
Stats
Lightfastness
Excellent in oil and acrylic, may be less LF in watercolor. May depend on pigment supplier
Some blue wool scales show highest marks (all 8’s). May have slightly less lightfastness in watercolor. At least one of the tests on Handprint show a slight falloff in tints.
Transparency
Transparent
Almost black in masstone, this creates some of the most vibrant blue tints and glazes
Toxicity
Previously thought to be in the category of Lower Concern, but may contain contaminants
Tubes made before 1982 or even 1986 may contain PCBs or dioxins. Current phthalos may also contain toxic contaminants depending on country of manufacture or other variables. Treat all pigments and paints with studio safety protocols. Please see the Artist's Guide to Health and Safety for information about the hazards associated with copper pigments. The author's most recent updated writing can be found through her site.
Tinting
Strong
One of the most powerful tinters. This color is one where it is almost always sold with extenders just to make the paint more usable.
Dry Time
Slow or very slow (6-18 days)
Chemical Name
Epsilon Copper Phthalocyanine
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