Operations of Silicon rubber for mold making Silicon rubber for mold making is a flowable liquid silicone, and the quality has nothing to do with the color. It consists of two component. Part A is a flowable liquid silicone rubber, part B is the curing agent. Firstly, after your previous work of dealing with the original model, take some liquid silicone rubber , add 2%-3% curing agent of the amount of silicon, and mix them evenly. Then after vacuum-pumping the mixture, you can pour it into the mold frame. The silicone mold will cured in 2-4 hours. Frequently asked questions of mold making silicone rubber Why does the silicone mould appear to be dry outside but wet inside? Because molding silicone rubber is a kind of condensation silicone rubber, which get solidified after absorbing moisture from the air. In order to provide a significant shelf-life for the silicon rubber, we will dry out the water in the silicon rubber. Solution: Add 0.05% water into the silicon rubber and Stir over a low speed briefly when you use it.