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Naphthol Red AS-D

PR112

Alternate Names

Naphthol Crimson

Naphthol AS-D

Pigment Description

This pigment crops up everywhere, and it is gorgeous in tints, but not nearly as lightfast as some of the other reds when lightened. Still this makes a lovely ingredient for certain pinks. Also called Naphthol Red AS-D (for clarity it is just one of several Napthols out there- and we’ve seen some confusion in how they are labeled so it may not be the only AS-D among them).

We were shocked to find out in Monona Rossol's writing on pigments that it has a similarity to dyes that cause cancer, may metabolize to a carcinogen, and cause methemoglobenemia as well as other problems-- see her research for more. It is often found in cadmium replacements, so its own toxicity is interesting to note.

Unfortunately Napthol Red PR112 also fades more than we would like to see in an artist color. Also, in oil this color showed surprising reactivity with lead white and will shift color in minutes. See Golden's Lightfastness Testing in Oils for more.

I used to absolutely adore this color and I only wish it were more lightfast. It makes the most interesting red tones in skin for portraiture- a lyrical red-pink with an orange hint. It was one of my most favorite colors that I used to use as a student before I found out it was not lightfast. PR112 is commonly found in artist and professional ranges. Sometimes even very respected brands will have it in their convenience blends as it creates such lovely mixes.

Resources

PR112 pigment data from David G. Myers, The Color of Art Pigment Database, Artiscreation.com

Information about PR112 from Bruce MacEvoy, Handprint Guide to Watercolors, General information about this class of pigments from Handprint,

Rossol, Monona. The Artist's Complete Health and Safety Guide. New York, NY : Allworth Press, 2001. The book is rather dated, updated information is available from her website.

Stats

Lightfastness

Reactive, Varies with Mixing White

This color was shockingly reactive in a couple of contexts. It performed both better than we expected as well as worse that we expected in Golden’s recent tests with various mixing whites. In Flake White this pigment is surprisingly reactive— it warranted a special section all to itself as one can watch its color shift in real time. Though more research needs to be done, we thought it was notable that PR112 did not perform well in Flake White and Zinc White. However, it performed better than the expected ASTM II in Titanium white in linseed oil. In both Titanium White and Titanium-Zinc white it performed at ASTM I. For more details check out Golden's report. Its lightfastness may also struggle in watercolors.

Transparency

Varies

In oils, paints formulated with PR112 range from opaque to transparent with the majority being in-between (semi-transparent or semi-opaque). There are a few paints that are listed as opaque. In watercolor it tends to be transparent.

Toxicity

Traditionally thought of in the Least Concern category, however new research suggests that it may be similar to a dye which causes cancer.

Monona Rossol’s writing about pigments and artist safety available on request here notes that this pigment has a similarity to dyes that cause cancer. Additionally it may metabolize to a carcinogen, and cause something called methemoglobenemia as well as other problems-- see her research for more. Treat all pigments and paints with studio safety protocols.

Tinting

Strong

Dry Time

Very Slow

In oils, the drying tends to be slow with one brand in the 10-21+ range. However a few are listed as 2-4 days, so driers may be used.

Particle Size

Fine

Chemical Name

monoazo, 3-hydroxy-2-naphthanilide, naphthol AS-D, naphthol carbamide

Dry Pigments listing PR112

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