Ultracal 30 Plaster for Mold Casting, Scenery, Dioramas, and Dentistry 5 lb Pack Resealable Bag Great for Model Making & Gaming by Capital Ceramics Ultracal 30 Plaster for Casting And Molding Quick setting, dense white plaster in water resistant bag. Ideal for patterns, figurines, commercial casts, and sculpture. It is not for making outer or mother molds, and it is not recommended for outdoor use. Full strength Ultracal 30 gypsum plaster, not cut with cheap plaster fillers Designed for strength and casting detail. Ultracal 30 is 30% to 50% harder than casting plaster and works much like plaster in mixing, pouring, and setting. Accepts liquid or crystal pigment colors and stains