Rublev Colours Chalk - Ground Calcium Carbonate

Dry grinding limestone reduces it to a powder without destroying its particle structure, which is essential in making strong chalk grounds and providing tooth on the surface of the grounds. The larger particle size of Rublev Colours chalk (when compared to precipitated chalk) keeps oil absorption low, which is ideal when adding it to oil paint and mediums. In painting grounds, it makes a durable surface with tooth for egg and casein tempera, distemper, encaustic, and oil paint.

Limestone (calcium carbonate CaCO₃) is a type of carbonate sedimentary rock that is the primary source of the material lime. It is composed mainly of calcite and aragonite, which are different crystal forms of calcium carbonate.

The Lucerne Valley limestone district contains enormous high-brightness, high-grade calcite limestone reserves. It lies in the California Transverse Ranges of Southern California and extends for about 40 kilometers along the north slope of the San Bernardino Mountains, overlooking the Mojave Desert. About 5% (12 thousand hectares) of the San Bernardino Mountains is underlain by Paleozoic carbonate rocks. This carbonate stratigraphic section averages about 1,500 meters thick, with white high-grade calcite limestone units ranging from 15 to 30 meters thick.

Add ground calcium carbonate to oil colours and mediums to create textural and bodying qualities to oil paint without affecting the colour. Ground limestone has a little colour in drying oil, so it can be added to oil paint without affecting the tint of the colour.

Warning: care should be taken when working with this product not to inhale the dust.