Why does the silicone mold 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.