Da Vinci Artists' Permanent Watercolor - Iridescent Naphthol Red, 15 ml tube

Pigment Information

This color contains the following pigments:

PR170-Naphthol Red

PW20-Mica

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.

Toxicity

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

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

PW20-Mica

Pigment Type

inorganic

Chemical Name

aluminum silicate

Chemical Formula

H2KAl3(SiO4)3

Properties

An off-white pigment with complex reflective effects, mica is often used with transparent pigments to create mixed pigments with interference and pearlescent effects.

Permanence

Mica is permanent and lightfast.

Toxicity

Although it is completely non-toxic and not bioreactive, fine particles may be irritating. This is of concern primarily for those exposed occupationally to dry mica powder. Breathing mica particles may cause lung fibrosis and pneumoconiosis.

History

Mica has been used as a pigment since prehistoric times.