Cernit Silicone Molds can be used with polymer clay as well as air-dry clays. Interesting effects can be obtained using Cernit Gel or other liquid clay. These molds can be baked in the oven at the temperatures needed to cure Cernit polymer clay. Take care not to expose them to excessive temperatures - tenting may be helpful. The molds are made of non-food silicone and are 7cm (2.75 inches) in diameter.