Why does my Original Sculpey turn color when baked? Some crafters have experienced that their white Original Sculpey will turn gray or lilac after baking. (when baked at regular baking temps) This is a characteristic of original white Sculpey. To be sure you are not over baking your clay recheck your oven thermometer. To prevent this you can baking it at a lower temperature (around 225) to reduce this effect, but the clay will be very weak. This is one reason why people who started with that clay tended to paint everything. A coat of acrylic gesso will cover a multitude of sins, and prime it for other colors. A convection oven may also improve your results. A convection oven don't have exposed heating elements and have a fan that blows the heat created by the hidden elements around the inside of the baking area.