No kiln needed. This is a premium quality, self hardening gray clay. It's specially formulated for modeling by hand, sculpting with tools or throwing on a potter's wheel. Prepared in moist form, it's ready to use. When completely dry, finished pieces are hard and durable, but not waterproof. After decorating, coat with shellac or varnish to seal it and make it water resistant. Details:Pale gray25 lb.Air-dry clayModeled objects are permanent without firing MoistNot waterproofReady to use Can be paintedNontoxic and AP Certified