To release silicone rubber from another silicone rubber mold, use a release agent that does not contain excessive amounts of silicone oil. We offer a specially formulated release agent designed for this purpose, which can be applied as a light mist coating and will not affect surface details.
Alternative Option:
You can also use petroleum jelly thinned with a solvent like mineral spirits. Just be sure not to leave any brush strokes on the cured rubber surface, as these will be reflected in the mold.