PY1—Hansa Yellow G

Pigment Type

organic, monoazo

Chemical Name

n/a

Chemical Formula

C₁₇H₁₆N₄O₄

Properties

This Hansa yellow is a transparent yellow. It has great brightness and tinting strength and its drying time ranges from average to slow.

Hansa Yellow makes more intense tints and cleaner secondaries than Cadmium Yellows, especially when mixed with other organic or modern colors like Phthalo Blue and Green. Because they are more transparent, they have great value as glazing colors.

Permanence

Hansa Yellow G has good permanence and lightfastness, particularly in the lighter shades.

Toxicity

Hansa Yellow pigments have no significant acute hazards, though chronic hazards have not been well studied.

History

Hansa Yellows were first made in Germany just before World War I from a series of synthetic dyestuffs called Pigment Yellow. Hansa Yellow G, introduced in 1910, was the first of these products to be commercialized. Hansa Yellow G was the standard yellow for printing inks until late in the 20th century, when stronger diarylide yellows began to replace it. It is still used a great deal in packaging, and for air drying paints.

Alternate Names

Light Fast Yellow G, Pigment Yellow G, Arylide, Arylide Yellow, Azo Yellow, Brilliant Yellow, Monoazo Yellow, Monolite Yellow, Permanent Yellow.

PBr7—Raw Sienna

Pigment Type

earth

Chemical Name

hydrated iron oxide

Chemical Formula

α-FeO³⁺(OH) or Fe₂O₃

Properties

Raw Sienna is a moderately dull deep earth yellow with medium tinting strength and excellent transparency. It is one of the basic permanent artists' pigments and is made from a form of limonite clay whose yellow-brown color results from ferric oxides. Raw Sienna is preferable to Yellow Ochre for creating flesh tones, due to its higher subtlety of color when mixed with white. It creates a bright Ochre when mixed with Cadmium Yellow and creates greens and grays when mixed with Ultramarine. Raw Sienna dries quickly.

Permanence

Raw Sienna has good permanence.

Toxicity

Raw Sienna has no significant hazards.

History

Raw Sienna has been used as a pigment since prehistoric times, although its current name came about during the Renaissance. It comes from the city of Siena, in Italy, and is short for terra di Siena, meaning earth of Siena. Sienna was famous for the mining and production of earth pigments from the Renaissance until World War II. Due to the depletion of clay deposits in Tuscany, Italian siennas now come from other areas, including Sicily and Sardinia.

Alternate Names

Italian Earth, Natural Brown Iron Oxide, Sienna.