The Amazing Mold Putty is a platinum based silicone mold rubber. The platinum base can become contaminated when it comes in contacts with specific materials ... such as tin, sulfur, and vinyl. These products are often found in clays, tapes, glues, plastics and some rubber stamps. What will happen is where ever the putty comes in contact with one of these different materials, they will simply not cure. However, every where the putty does not come in direct contact with the materials, it will cure absolutely fine. If you are not sure whether the item you are about to mold using the Amazing Mold Putty contains one of these materials, it is highly recommended to mix up a very small batch of the putty and press it over a small area of your piece. Allow it to sit for 20 minutes and then remove. Notice the surface of both your original as well as the mold. Drag your finger across the surfaces to see if the mold surface smears. If it does, I would not recommend making the mold until you have either completely coated the original to protect the putty from the surface or simply choose type of master to test and then mold.