It’s fairly rare to find PB15:2. It’s one of several phthalo blues, and it seems like more of a red shade. The main categories are called Green Shade, which leans more cyan, and Red Shade, which tends to be a middle blue that leans slightly more toward indigo relative to other phthalos. The number after the colon in pigment code signifies this specific variety, which in this case is sometimes called Red Shade. PB15:1 is a more commonly found red-shade variety. Further general information can be found on the entry for PB15 as well as the in-depth article on Phthalo blues.
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, however it may contain driers. It seems to frequently contain additives, stabilizers, and extenders. 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. Phthalo Blue sometimes also contains dioxins and PCBs depending on how it was manufactured.
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.
