A family of high-strength gypsum cements used for molds, castings, models, architectural ornament, and sculptural reproduction.
Hydrocal is a trade name for a family of high-strength gypsum cements used in casting, mold making, model making, architectural ornament, and sculpture. Hydrocal White is formulated for both solid and hollow casting and is substantially stronger than ordinary molding plaster.
Because of its strength and ability to reproduce fine detail, Hydrocal is commonly used where a more durable gypsum casting is required. Different Hydrocal products have different working and strength characteristics, so water ratios and handling procedures should follow the manufacturer’s specifications.
Etymology
Proprietary product name used for a family of gypsum cements manufactured by USG.
Sculptor Notes
Hydrocal should not be treated as simply another name for plaster of Paris. Its greater strength can be useful for thin cast sections, durable positives, mother molds, and studio models, but the specific Hydrocal formulation matters.
References
https://www.usg.com/en-US/p/product/hydrocal-white-gypsum-cement-105618; https://en.wikipedia.org/wiki/Glossary_of_sculpting