As a specially formulated art supply grade plaster, PLASTERMIX Plaster of Paris Casting Material is activated by using 2 parts casting material to 1 part cold water. Check ‘How To Make Plaster’ section below for instructions and best practices. Hardening or drying times for PLASTERMIX will vary with mold thickness. As a general guideline, please follow these drying time allowances:For smaller moldings, less than 1” thick, allow 20 - 30 minutes.For larger moldings, more than 1” thick, allow 45 – 60 minutes. Sandtastik® PLASTERMIX is the perfect craft for kids birthday parties, classroom projects, camps, and at home.Colour: Arctic WhitePackaging: 1 kg (2.2 lb) BagAges: 4+ (adult supervision)Certif: ACM 'AP' Non-toxicConforms to ASTM D-4236