Castor Wax

Castor Wax is a non-hygroscopic organic derivative of castor oil. Use as a rheology additive in oil and alkyd paint, to add thixotropic body and prevent oil separation. Does not react with pigments and vehicles and does not detract from the durability of paint. Assists in the stabilization of water-in-oil emulsions. Add 1–2% of total pigment weight.

Castor wax is primarily used as a rheological additive to add thixotropic body and increase viscosity, reduce settling of pigments and extenders, control sag without impairing flow to produce optimum leveling in paints, control liquid penetration into porous surfaces and has no adverse effect on durability and lightfastness and is non-yellowing.

Solubility

Castor wax exhibits relatively high solubility in hydrocarbon solvents (such as mineral spirits). It is insoluble in water and alcohol, but is readily soluble in benzene and common organic non-polar solvents when warm.

Storage

Castor wax should be kept in a cool, dry location. It has a shelf life of four years from date of manufacture.

How to Use

The optimum use level of castor wax varies depending on the vehicle and on the desired degree of thickening. A typical starting use level is 0.2% to 0.8% by weight of the total paint. Castor wax should be added to the vehicle before grinding with the pigment, preferably by mixing in the vehicle for about five minutes before other components are added. When incorporating castor wax a lower and an upper processing temperature must be observed. A minimum temperature of about 43° C (110° F) is necessary to build the thixotropic structure properly. If a 55° C (130° F) temperature is exceeded, soft gel-like particles may appear on return to room temperature. The presence of aromatic solvents lowers this upper temperature limit. Should this limit be exceeded, the formation of particles can be prevented by continuous stirring during cooling to 45° C (113° F) or below. Within the prescribed temperature range, castor wax should be subjected to as much stirring as possible during processing. The more intense the stirring or grinding action, the more pronounced and immediate is the effect.