First off, it’s important to remember that polymer clay contains plasticizers, chemicals added to PVC in order to make it soft and pliable. In order for polymer clay to become hard, these plasticizers must be removed. How? The answer lies in baking! The baking process involves high temperatures, which is necessary for removing the plasticizers from the clay. (This is in fact why polymer clay doesn’t completely air dry — because it requires baking in order to fully cure.)
Baking polymer clay is indeed a science, and depending on the brand of the clay, different temperatures and baking durations are required. For example, FIMO clay bakes at 265 degrees Celsius for 30 minutes, whereas Scupley clay bakes at 275 degrees Celsius for 15 minutes. In addition, it is critical to not overbake or underbake the clay. Underbaking results in the clay crumbling, and overbaking can result in burning the clay, which releases toxic hydrochloric gas fumes as the plasticizer molecules are removed via heating.
Here’s a great video that shows you how to bake polymer clay (among other baking basics!):
There is an alternative to baking polymer clay in a kitchen oven, if you’re concerned about baking food in the same oven.
This is a craft oven, which is specifically designed for baking polymer clay. There are various brands, but I found that this one was one of the best. (There are many reviews about the oven on YouTube!)
That’s it for this post! Stay tuned for more clay science!