yes
It is not reversible once the ingredients have been mixed in a bowl, nor when the cake has been baked in an oven.
For Fimo Polymer clay and Sculpey Polymer clay should be baked in the oven on a baking sheet covered with foil or baking parchment for about 20 minutes to 1 hour at 130 C / 275 F Or...5-3 hours at around 220, and let it cool in the oven...:) "The information is on the back of the packages" Fimo & Sculpey clay requires an oven, heated to 265 degrees, and bake clay for 30 minutes. And yes, use foil or baking parchment with old cookie sheet. (use the cookie sheet only for clay, never for food)
the large oven used for baking bricks is called a kiln
Clay is actually not poisonous in the oven, everybody can bake clay in the oven but not in the oven?
The cake is baking in the oven.
No. Modeling clay contains oil that keeps it soft and never hardens. Polymer clay does not have an oil, it hardens when exposed to heat. polymer clays are often called "oven-bake clay"because you can make stuffs such as pendants, brooch, earings and other accesories using polymer clay by baking them in the oven. YES, i said oven. PLEASE be safe and never try to put them in the microwave.
yes it is
I doubt a toaster oven would reach sufficient heat to bake clay. Contact a potter, or pottery society, who could be able to help you with alternative methods for baking clay. The link below has some recipes for small clay (bakers' dough) objects for making in a domestic kitchen.
reversiublrt
a clay oven is an oven made out of clay which egyptians used to cook bread in
Baking powder (baking soda + some acid salts) will release CO2 (carbon dioxide gas) when placed in water. So, even though, in theory, all reactions are reversible, it is not likely that baking powder in water is reversible once the CO2 gas has formed.