Rublev Colours Pigment Cobalt Zinc Blue - 100 g

All cobalt blue pigments are chemically inert, absolutely insoluble, have good hiding power and excellent heat stability, and show excellent lightfastness and weather resistance.

Pigment Blue 72 is a modification of cobalt aluminate blue spinel pigments (Colour Index Pigment Blue 28). Cobalt aluminate blue pigments are the most durable blue pigments commercially available. They have excellent chemical and heat stability and can be used in chemically aggressive environments and exterior applications without fading.

Water-Based Paint

Cobalt blue is a semi-transparent pigment with moderate tinting strength in most water-based paint. When it dries, it appears lighter and less saturated. Although pigment particles are very fine, they flocculate, giving a grainy appearance in watercolor. Differences in how the pigment is ground and mixed lead to considerable differences in its performance.

Oil-Based Paint

Cobalt blue is a semi-transparent pigment with moderate tinting strength in oil-based paint. Differences in how the pigment is ground and mixed can lead to considerable differences in appearance.

Oil Absorption and Grinding

Cobalt blue absorbs a moderately high amount of oil, about 55 grams of linseed oil per 100 grams of pigment, to make a paste. It has been noted in some manuals that the pigment works better as a watercolor than it does in oil and is highly valued on that account among moist colors used by artists. Grinding it for artists' use in oil will require 35 percent dry pigment to 65 percent by weight of poppy seed or walnut oil, either of which some artists prefer to linseed oil. Cobalt blue has a greenish tone that is more or less reddish blue when viewed under incandescent light.

Toxicity

Cobalt blue is not considered toxic; however, care should be used in handling the dry powder pigment to avoid inhaling the dust. All toxicological studies showed no signs of toxicity to humans or the environment.

In animal studies, cobalt blue pigments did not display acute toxicity. No acute irritant effect was shown in tests to determine the acute irritation of the skin and mucous membranes. No statistically significant results were found in studies on rats to determine the carcinogenic potential. Soluble cobalt compounds, as well as cobalt metal, may have a sensitizing effect. However, none have been reported during the experience of many years of handling cobalt blue pigments.