Holbein Artists' Watercolor - Vermilion Hue, Half Pan

This color contains the following pigments:

Naphthol Red AS-D

Permanent Red

Diarylide Yellow 81

Pigment Name

Naphthol Red AS-D

Pigment Type

organic, monoazo

Chemical Formula

C24H16Cl3N3O2

Properties

This Naphthol Red is an intense scarlet red pigment that is heavily staining. It has an average drying time. It is semi-transparent and has relatively poor covering power.

Permanence

This Naphthol Red has been rated as having excellent lightfastness under ASTM testing, but other testing methods have demonstrated some tendancy for the color to fade with exposure to strong ultraviolet light. It has been considered a replacement for less lightfast naphthol reds such as PR3. Not suitable for exterior use.

Toxicity

Naphthol Reds are not considered toxic. Naphthol Red AS-D may cause eye, skin, or respiratory irritation. Contact with dry pigment should be avoided.

History

Unknown.

Pigment Name

Permanent Red

Pigment Type

organic, monoazo

Chemical Name

beta-oxynaphthoic acid lake

Chemical Formula

Properties

Beta-oxynaphthoic acid (BONA) lake pigments vary in their hue and other properties, depending on what metals they form a salt with. Both pure and mixed metal salts are used. They tend to have high tinting strength and good stability and lightfastness.

Permanence

Beta-oxynaphthoic acid lake pigments tend to have high tinting strength and good stability and lightfastness, but results vary with the application, and the presense of titanium dioxide may reduce lightfastness. 

Toxicity

History

Beta-oxynaphthoic acid may have been synthesized as early as 1887. Commerical use of BONA lake pigments began in the 20th century.

Pigment Name

Diarylide Yellow 81

Pigment Type

organic, disazo

Chemical Name

diarylide yellow H10G

Chemical Formula

C36H32Cl4N6O4

Properties

Diarylide Yellow is a semi-opaque, moderately staining, intense deep reddish yellow pigment with good tinting strength and excellent heat resistance.

Permanence

Diarylide Yellow 81 is considered to have very good lightfastness, 7 on the blue wool scale (1-8).

Toxicity

Diarylide Yellow has no significant acute hazards, but its chronic hazards have not been well studied.

History

Diarylide Yellow comes from a family of azo pigments called diarylide. These yellow hued pigments were developed around 1940 and are very important in printing inks.