The Probert Encyclopaedia of Science & Technology

ULTRAMARINE

Ultramarine is a blue pigment derived by grinding the semi-precious stone lapis lazuli. Ultramarine is also produced artificially from a mixture of silica, china clay, sulphur and soda ash, subjected to prolonged calcination. Ultramarine is attacked by acids, but has a good resistance to alkalis. Ultramarine has a good staining strength and opacity in water, but poor opacity and only moderate staining strength in oil.
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