Schmincke Horadam Aquarell Artist Watercolor - Cobalt Blue Deep, 15 ml tube

Pigment Information

This color contains the following pigments:

PB74-Cobalt Zinc Silicate Blue Phenacite

PB28-Cobalt Blue

Pigment Name

PB74-Cobalt Zinc Silicate Blue Phenacite

Pigment Type

inorganic

Chemical Name

cobalt zinc silicate

Chemical Formula

(CoZi)2SiO4

Properties

Cobalt-zinc silicate is semi opaque and semi-soluble in water. It produces a warmer and darker blue that standard Cobalt Blue (PB28), and is used most often in glass and ceramics.

Permanence

Cobalt-zinc silicate is extremely lightfast and temperature stable.

Toxicity

Cobalt-zinc silicate is toxic, and its toxictiy may be of greater concern that for Cobalt Blue (PB28) because it is semi-soluble in water.

History

Since the discovery of processes for mining Cobalt Blue (PB28) in the 19th century, additional processes for manufacturing and purifying other cobalt salts have become available. Their use as artist pigments has followed.

Pigment Name

PB28-Cobalt Blue

Pigment Type

inorganic

Chemical Name

cobalt(II) oxide + aluminum oxide

Chemical Formula

CoO + Al2O3

Properties

Cobalt blue is a semitransparent pigment with low to moderate tinting strength. When it dries, it appears lighter and less saturated. Pigment particles are large and grainy. Differences in how the pigment is ground and mixed lead to considerable differences in its performance among various manufacturers.

Permanence

Cobalt blue is absolutely lightfast and extraordinarily stable. The stability of cobalt salts at high temperatures make them the standard for blues used in ceramics and glassware.

Toxicity

Cobalt salts are toxic. Avoid respiratory and skin contact. Soluble cobalt may cause irritation and allergic reaction through contact with skin. It is considered a possible carcinogen.

History

Since ancient times, smalt blue has been used to color glass and ceramics. Cobalt salts, which give smalt its characteristic blue color, were identified in the 18th century. Techniques for manufacturing Cobalt Blue, a chemically pure salt of cobalt and aluminum oxide, were developed in 1802.