ACTIVA-Plus Natural Self Hardening Clay. Plus clay is a premium quality natural self hardening clay. It s exceptional plasticity and ultra fine grade allows for excellent detail and versatility. It air cures to superior strength and durability (will not crumble) with minimal shrinkage. Can be carved; sanded and drilled when dry and accepts virtually any finish. If desired Plus clay can be kiln dried. This package contains 2.2 lb/1kg of white clay. NOTE: clay lightens in color as it dries. Imported.