Air Dry Clay in WhitePlus Clay is a premium quality, natural, self-hardening clay. Its exceptional plasticity and ultra fine grade allows for excellent detail and versatility. It air cures to superior strength and durability (will not crumble when dry), with minimal shrinkage. Plus Clay can be carved, sanded, and drilled when dry, and it will accept virtually any finish. Plus Clay with a thickness of 1/4 inch will take approximately 24 hours to dry. Drying times will vary depending on the thickness of your piece and the amount of humidity in the air.