Solidify moulded clay creations by baking them for a few minutes in a home oven. Polymer clays are often marketed as "oven-ready" and "oven-bake" to let buyers know that they can be sculpted right out of the package and cured quickly in the oven. Air-dry clays are not intended for oven drying and take much longer to cure than oven-baked varieties. Monitor the time and temperatures carefully during the drying process to avoid burning and discolouration.
Read the packaging that came with the clay for the manufacturer's instructions and to make sure the clay can be safely oven-dried.
Place an oven thermometer on the centre rack of the oven and set the temperature to 135 degrees Celsius / 275 degrees Fahrenheit.
Line a sheet pan with aluminium foil or a silicone mat and gently set the clay on the pan.
Measure the thickness of the clay piece in its thickest section.
Set a timer for 15 minutes for every quarter inch of thickness in the thickest section. A clay sculpture with a half-inch of maximum thickness would require 30 minutes on the timer.
Open the oven door after it has been heating up for at least 15 minutes and read the temperature on the internal oven thermometer. Make adjustments to the oven's temperature settings until the internal thermometer reads 135 degrees C / 275 degrees F.
Slide the sheet pan into the centre of the preheated oven and start the countdown on the timer.
Remove the sheet pan and set it on a heat-resistant surface to allow the clay to cool. Approximately 30 minutes per quarter inch of maximum thickness is a good rule of thumb for cooling times.