Although molds are stretchy and withstand many castings, there are several factors that may contribute to tearing, such as release agent used (or not used) to ease the pulling, abrasive particles in cement mix, leaving the molds folded or not cleaning them.
Here are a few tips that will help your molds last longer and work better.
1. For the molds to retain their shapes store them in a single layer, do not pile them up.
2. After using clean the mold with tepid water and soap, don’t use abrasive products. Don't forget to clean the mold between the castings, especially when using pigments or different colour cement. Gently remove the dry particles of concrete with soft sponge and soap to avoid scratching the silicone surface.