Oven Hardening Clay: Polymer clay remains workable until cured. Curing occurs when crafted clay is heated with a household microwave or oven at temperatures from 265 °F (129 °C) to 275 °F (135 °C) sustained for 15 minutes per 14 inch (6.4 mm) of thickness. Air Hardening Clay: This clay does not need a kiln and will dry on its own. It is suited to free-form sculpting and can be sanded, drilled, painted, or varnished once dry. Characteristics: 110 colors
