Alumilite's High Strength 2 The High Strength 2 silicone mold making rubber is a great all purpose silicone as it is flexible, extremely tear resistant, has a low viscosity that does not require degassing (although always recommended if capable), and is very easy to mix. The High Strength 2 is a tin base silicone. It is recommended for one piece molds, molds with undercuts, multi piece molds, and molds that require a very high tear strength.