BLUE Art Supply Pigment Database Watercolor Acrylic Ink Pencil Color Chart Swatch
Artist reference guide to Blue pigments in art supplies. Color chart swatch cards of common pigments in watercolor, acrylic paint, inks and pencils. Includes lightfast or fugitive information, index by pigment number code, brand, manufacturer color name, how the color appears in masstone (full strength) or diluted (with water). Each image displays opacity, lifting (erasing with a damp brush), and layering (glazing a second coat after the first has dried).
Often mislabeled as lightfast in watercolors. Unfortunately PB27 always fades in sun, but recovers in shade. Manufacturers who are aware of the issue may mark it as stable (LF I /BW8/max star lightfastness depending on the country) due to it's ability to regain color after being removed from light. Paint should not need to be taken off the wall for a nap in a dark corner for it to be considered lightfast. I avoid this pigment if planning to sell a painting or display it in a gallery, as a buyer is likely to hang it in a well-lit room. It is only stable in shady museum lighting conditions. Artwork made with Prussian Blue WILL fade from window lighting, which can be noticeable within weeks in rooms with large windows or locations closer to the equator.
"BUT Kim, x brand of Prussian Blue is lightfast!" I'm sorry for the bad news, but it's chemically impossible for PB27 to be totally stable. It is produced by oxidation of ferrous ferrocyanide salts. Sun bleaches the FeIII (Iron) which requires time to re-oxidize away from light. Prussian has a reaction to UV light on a chemical level, which is only reversible over time in darkness. Don't take my word for it though, feel free to do your own testing, google search or do some PB27 research on Dick Blick, Handprint or other reputable sources that will confirm this. I realize that most artists and paint companies trust ASTM lightfast ratings, but I advise caution because their testing methods are limited. They do not always correctly distinguish between masstone and diluted, even when a pigment has been proven to fade in lower % tints. They also test mixes with white paint, which is not the same as just diluting with water as in watercolor painting. It's also important to note that sometimes a larger company who supplies pigment powder to the paint manufacturer supplies them with a lightfast rating (such as ASTM I-IV, Blue Wool 1-8 Scale or a 3-5 star system) which the paint maker may not double check for accuracy.
Each Prussian blue watercolor I've tested in every professional artist grade brand (including Daniel Smith, Mission Gold, Paul Rubens, W&N along with student grade brands) have all faded with UV exposure within 1-3 months. This is generally a fault with the ingredient, PB27. Fun thing to see though, is if you put it in a shady drawer for a week the color will almost regain full strength. The only variance between brands is how MUCH it will recover AFTER fading. Prussian Blue takes time to become darker again in the shade. Some brands can make a nearly-full recovery in several weeks, which may be due to the differences in pigment source and any protection from binder additives. Overall, PB27 is a very unique and interesting pigment, but one that is not reliably stable. It is likely that the original rating came from some one who collected results and let them sit in the shade before comparing them, or decided that since it was able to recover it was OK. To me this simply defies the definition of a "lightfast" rating. If the color is not stable in light, I consider it fugitive.
PB60 Indanthrone Blue:
Swatch card template available for download here, or get the rubber stamp here. Swatch cards were painted on Legion Black or Arches Cold Press 100% cotton watercolor paper. Paper and brushes are available at Jackson's or Amazon here:
Where to buy art supplies shown on this page:
The following affiliate links are to places I have purchased my art materials. When available I'll include multiple reputable stores so you can compare and decide where you'd like to shop. Dick Blick ("DB" links below) is a large art supply chain store here in the USA that ships worldwide. Jackson's ("Jack" links below) is a great UK based art supply store which also ships worldwide, but carries some harder to find European products with quick low cost shipping to the USA. Amazon USA ("Ama" links below) often offers unique brands, including small business and Chinese off brand watercolor sets, that can not be found anywhere else. As an Amazon associate, I earn from qualifying purchases.
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Interested in other ways to help this project? Visit me at Kimberly Crick Art on YouTube or Patreon. If you have supplies that you would like to donate, such as watercolor dot cards or samples from your company that you would like reviewed or displayed in this pigment directory, please email me at email@example.com or use the contact form with details. Thank you :)