Van Gogh Oil Pastel - Scarlet 334.5

Pigment Information

This color contains the following pigments:

PR170-Naphthol Red

PR112-Naphthol Red AS-D

Pigment Name

PR170-Naphthol Red

Pigment Type

organic, naphthol AS

Chemical Formula

C26H22N4O4

Properties

Pigment PR170 is a bright deep red with bluish undertones. It has an average drying time. It has two crystaline forms that differ significantly in opacity. The more transparent form (F5RK) tends to be more bluish and is less lightfast.

Permanence

The lightfastness and weatherfastness of Pigment PR170 varies, depending on the application and the crystaline form. The opaque form (F3RK) has very good lightfastness, and is more weather resistant. The transparent form (F5RK) has lightfastness that is considered acceptable in pure applications, but it fades more in tints. Neither form is considered suitable for exterior use.

History

Naphthol pigments are actually dyes that are "laked" to form pigments. First developed by the German chemical company Hoechst A.G. before World War I, their use in artist paints began in the 1920s. Pigment Red PR170 is a Naphthol AS pigment, chemically related to the diarylide yellow pigments. The Naphthol AS pigments comprise a range of reds. They are used in plastics, textiles, and printing inks.

Pigment Name

PR112-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.