Hydrocal is a brand name for a white gypsum
cement made and marketed by the US Gypsum Company. It is
available in a number of different formulations and is most commonly
used by glass artists as a mold material (or "investment").
Hydrocal, which is often mixed with silica
flour and other refractory materials to make a casting mold, is
especially useful when a strong mold is required. It expands
to nearly twice its original size when mixed, and is ideal for bas
relief molds or for molds that have thin sections requiring
Because Hydrocal sets rapidly, it must be
worked very quickly when mixing and pouring. Be sure to use
cooler water to help slow the setting process. When cured,
Hydrocal is a very white color. It can be easily carved, and
takes detail well. Additional pours will bond easily to
previously poured Hydrocal.
For more on Hydrocal, see the
US Gypsum website at
Copyright 2005 Brad Walker.
All rights reserved.