For the last two years I have been wearing a hand brace on my left hand to prevent further wear injury. I wanted to make a polymer clay brace to wear so a friend, Pepper Kaminoff, made a mold of my hand so I could shape the clay on it and bake in the oven.
Now, here is what I learn form this project. If you are cooking some thing on a plaster mold, cook it two of three times as long as you would usually. The first brace I made was cooked 45 minutes at 280 degrees Fahrenheit. I included a test pieces and couple of other small objects. The test pieces was fine as were the other objects but the brace broke. My mistake as not having the test pieces stuck on to the plaster hand mold. Mark two was made the same as the first one but I put a test piece right on hand mold. after and hour the test piece was still brittle so I cooked it another hour and if was fine. I think the internal temperature on the plaster mold has to get to clay cooking temperature before the clay will cure properly.
LESSON LEARNED - IF YOU COOK SOMETHING ON A MOLD, MAKE SURE THAT YOU HAVE A TEST PIECE IN CONTACT WITH THE MOLD.
If you live in British Columbia Canada and have hand problems I recommend the Westside Hand Clinic where the original hand brace was made.
Thank you Pepper