The most widely used gypsum cement with the lowest expansion rate available. Ideal
for casting polyester, epoxy resins, as well as being the industry standard for casting of foam latex. Highest strength with less tendency to warp. 30 minute set time

Water Plaster Ratio
Variation in ratio will result in variation in strength with dryer mixtures being generally stronger but complete and thorough mixing of the product dictating a wetter mixture. The best method to control water to plaster ratio is to carefully weigh the two components. Volumetric measurement methods are to be avoided.

Soaking and Mixing
Add plaster to the water not water to the plaster. Sift or strew plaster into water slowly and evenly. Do not drop handfuls of plaster into the water. Allow the plaster to soak in the water for 2-4 minutes. After soaking, mix water and plaster for 2-5 minutes. Hand mixing is O.K. for batches to 5 lbs. but USG recommends the use of a power mixer for larger batches. Thorough mixing is key to maximizing the crystalline interlace structure of the plaster mix.

        ... and more