Any piece created with the air dry clay from our Air Dry Clay Kit or Air Dry Clay add-on hardens with the help of nothing but - you guessed it - air. Any piece created with the ceramic clay from our Ceramic Clay Kit or Ceramic Clay add-on requires firing in a professional kiln at a pottery studio to become waterproof and (depending on the glaze used) food-safe. If you don’t need your decorative ceramic clay piece to become waterproof or food-safe (or can’t find a nearby kiln), you can simply let it air dry. Just remember: it will be very delicate + will dissolve when wet.Click here to get help finding a nearby kiln.