Michael Harding Artists Watercolor - Olive Green, 15 ml

Pigment Information

This color contains the following pigments:

PR101-Red Iron Oxide

PY180-Benzimidazolone Yellow

PB15:3-Phthalo Blue

Pigment Name

PR101-Red Iron Oxide

Pigment Type

earth, synthetic

Chemical Name

iron oxides (synthetic), iron oxide, silica, alumina, lime, and magnesia or hydrated iron oxide

Chemical Formula

Fe2O2 or Fe2O3 x H2O

Properties

Red iron oxide varies in hue and transparency, depending on hydration and slight impurities. Indian Red is a slightly duller, deep brick hue with a bluish undertone. It is very dense and opaque, with excellent tinting strength and covering power. It is dependable when mixing with all other permanent pigments and yields good flesh tints when mixed with Zinc White. It is the synthetic version of PR102, which is a pigment made from earth reds, or natural red iron oxides, and the names applied to PR101 and PR102 often overlap. The synthetic red iron oxides have mostly replaced natural red iron oxides and are brighter, stronger, finer, and more permanent. Indian Red is the highest grade bluish shade. Light Red, English Red, and Venetian Red are yellowish shades. Mars Violet is a dull and subdued bluish or purplish oxide.

Permanence

Red iron oxide is very lightfast with excellent permanence.

History

Natural red iron oxide comes from the mineral ore hematite, called bloodstone by the ancient Greeks from the word hema, meaning blood. It is one of the oldest pigments, has been used by every major civilization, and was an important mineral for medieval alchemists. It was not widely used in artists' materials until the 17th century and was not produced in large quantities until the 18th century.

Pigment Name

PY180-Benzimidazolone Yellow

Pigment Type

organic, benzimidazolone

Properties

Benzimidazolone Yellow 180 is a transparent greenish yellow pigment with high tinting strength. It is very similar in hue to PY74, a Hansa Yellow pigment with even higher tinting strength that was the traditional yellow used in CMYK (four color) process printing.

Permanence

Pure tones of Benzimidazolone Yellow 180 have excellent lightfastness. Tints with white are considered less lightfast. Benzimidazolone Yellow 180 is considered to have greater lightfastness than PY74, which it often replaces in printing technology.

History

Benzimidazolone pigments were developed by Hoechst in the 1950s and 1960s. Benzimidazolone Yellow 180 is used in printing and plastics. Although it is more expensive than PY74, a Hansa Yellow, and has lower tinting strength, its lightfastness often makes it the yellow of choice in four color process printing.

Pigment Name

PB15:3-Phthalo Blue

Pigment Type

organic

Chemical Name

beta copper phthalocyanine

Chemical Formula

C32H16CuN8

Properties

Phthalo Blue PB15:3 is a structural variant of Phthalo Blue PB15 that produces more greenish tones.

Permanence

Phthalo Blues are completely lightfast and stable and are permanent for all paint uses. They are currently used in inks, coatings, and many plastics due to their stability and are considered a standard pigment in printing ink and the packaging industry.

History

Developed by chemists using the trade name Monastral Blue, the organic blue dyestuff now known as Phthalo Blue was presented as a pigment in November 1935 in London. Its discovery was accidental. The dark color was observed in a kettle where a dye was being made from a British dyestuff plant. The demand for such a pigment came from commercial printers who wanted a cyan to replace Prussian Blue.