Fimo clay is a chemically based material that won't harden until you bake it in the oven. You can work it repeatedly over a long period of time, which makes it ideal for larger projects. It isn't suitable for young children, but you can supervise older children while they use it and bake their creations for them.
Preparation and Sculpting
Before you can use Fimo clay, you have to knead it to make it elastic and workable. To make kneading easier, use small pieces or add a medium such as "Mr. Quick" to the clay. You can rework Fimo clay repeatedly if it hasn't been oven-hardened.
The manufacturer recommends useing a sheet of glass as a work surface, since it can be put into the oven along with the finished work, but you can cover your work surface with a disposable plastic tablecloth or a washable vinyl cloth if you prefer.
You'll need some tools to roll out the clay, such as a rolling pin or a tin can, and to make details in it, such as needles, knives and spatulas. If you're making a large, thin or tall piece, it's best to support it with a wooden or wire frame (armature). You can store an unfinished piece in a plastic bag or a can to keep it dust-free.
Use coloured clay and make special effects by kneading several colours together. Roll the clay into strips and knead two strips together for a marbled look.
Baking and Finishing
Bake the clay in any home oven. Preheat the oven to 129 degrees C and place the clay on aluminium or glass baking trays. Bake for 20 to 30 minutes, depending on the thickness. The clay doesn't shrink in the oven, and will reach full hardness when it cools. You can add fresh clay to a finished piece and harden it in the oven.
Use a two-stage glue if you'll be gluing finished clay pieces to metal. For any breaks in the clay, or to join two pieces of hardened clay, use a super glue-type gel.
Paint the finished work with acrylic paints. To deepen the colour of Fimo coloured clays, finish with Fimo varnish in a mat or gloss finish.
You can store any unbaked Fimo clay for several years in its original packaging, aluminium foil or plastic bags.
According to Eberhard Faber, the manufacturer, "Fimo clay consists of PVC and plasticiser (phtalic acid esters of straight chain alphatic alcohols, from C6 upwards)."
The manufacturer warns that Fimo clay is for children age 8 or above and requires adult supervision at all times. The clay is not to be put in the mouth. Keep all children under age 8 and all animals away from the clay. Store finished toys or figures out of young children's reach. Wash your hands after using the clay. Clean all the tools and other equipment that you've used. Don't eat, drink or smoke in the area where you're using the clay.
Don't exceed 129 degrees C when hardening the clay, since harmful gases can be released if the clay is heated to higher temperatures. Use an oven thermometer to check the temperature. Never use a glass thermometer. Do not use a microwave oven. Children are not to be involved in the hardening process; it should be performed by an adult.
If you accidentally overheat the clay and someone inhales poisonous gases, get the person outside into the fresh air and get medical attention immediately. Take the Fimo clay and the packaging with you.