PB15:4

One of several Phthalo Blues, more general information can be found in the entry for PB15 as well as the in-depth article on Phthalo blues. A high chroma powerhouse of a blue which reveals its chroma in tints. This color is sometimes used in printing inks as well as in Manganese Blue Hue substitutes. It tends to be a light, transparent cyan and some brands even call it Phthalo Blue Light.

We’ve encountered it in a couple of oil paints which tended to be lovely, bright, thin cyans, which were different in character from most phthalo blues we’ve tried. In some tests the paint alligatored (wrinkled) perhaps because the paint was so oil-rich. When heavily extended it can be too weak of a pigment to replace manganese blue, but can emulate some of the transparency of PB33.

Along with PB15:3 it shares the "b form" of phthalo blue (C.I. code 74160). This is listed as ASTM II is watercolor, and may fade a bit in tints.

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 (and may contain driers). It seems to frequently contain additives, stabilizers, and extenders. 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.