Sculpey clay is favored among craft enthusiasts because the oven-bake polymer clay can be easily fired at home. If you follow the formula for baking and look for visual and tactile cues, you'll always know when your clay is done.
Baking isn't the only way to cure polymer clay, but it's the easiest and most recommended way. If you follow the directions on the package, you'll be given the correct temperature and baking times for your piece.
The Original Sculpey formula is 275 degrees Fahrenheit baked for 15 minutes for every 1/4 inch thickness. So if your piece is 1/2 inch thick you would bake it for 30 minutes, and if it's 1 inch thick you would bake it for an hour. This formula is the same whether you are making figurines, beads, decor or any other clay project.
If you are using other Sculpey clay products besides Original, the firing parameters are different. Refer to the proper baking temperatures and times on Sculpey's official FAQ page.
Things You'll Need
Unfired Sculpey clay piece
Oven or toaster oven
Oven-proof glass or metal baking tray or dish
Foil or parchment paper
Ruler or tape measure
Preheat your oven to 275 F. Place an oven thermometer inside your oven to ensure it reaches the desired temperature and remains consistent. You can use a toaster oven instead of a regular oven, but never use a microwave.
If you use your baking tray or dish to prepare food, line it with foil or parchment paper. This step is not necessary if you use it strictly for firing clay.
Do a test firing to ensure the accuracy of your oven temperature. Pinch off a small amount of Sculpey clay and form it into a circle 1/2-inch wide and 1/4-inch thick. Bake it on your baking tray or dish for 15 minutes. Then remove the test piece, and let it cool. Inspect the clay -- if you see any dark spots it means your oven is too hot. Lower the temperature by 10 degrees, and perform the test again with a new piece.
Put your clay piece on the baking tray or dish, and bake it for the time you have calculated based on its thickness. Never increase the baking temperature or bake for longer than suggested unless you are adjusting for special conditions.
Remove the baking tray, and allow your piece to cool completely.
Translucent clay sometimes scorches easily, so you're better off reducing the temperature by 18 degrees and doubling the baking time.
For altitudes above 3,500 feet, increase the temperature by 5 degrees, extend the baking time an extra 10 minutes -- and when in doubt, test, recommends polymer clay expert, Nancy Ulrich.
If your oven is inconsistent, or has a quick heating cycle, you might burn your clay. So start with the oven 20 degrees lower than the instructions say, and after 10 minutes of baking increase the temperature to the proper level and bake your piece for the full recommended time.
Visual and Tactile Clues
When you remove your Sculpey piece from the oven, you might not think it's done. The color should have darkened slightly, but not changed substantially, and there should be no brown edges or burnt spots. It will still feel a bit soft -- but don't worry, that's a good sign. Your piece will harden up to its proper finished state by the time it cools completely.
Once it's cool, you will know you have cured it properly if it's difficult to break. A thin piece might bend, but it will not break easily. If you slice it, the cut will be clean rather than crumbling. If your piece breaks or crumbles, do another test firing and adjust if needed.
Find unique Sculpey projects and learn different techniques and finishes for free at Sculpey University.