Ultracal 30 Gypsum Cement 2.5 lbs - Plaster - For Mold Making and Casting, Ideal for Latex Molds! Takes Excellent Detail Ultracal 30 Gypsum Cement for Professional Molding and Plaster Casting Very Low Expansion, Very Durable. Ideal for Latex Molds. Takes Extremely Fine Details! Professional Use Only. Can Get Hot When Hardening!