Mold-release agent for producing thermoset moldings with a hydrophobicized surface, where the agent comproses (I) at least one compound with mold-release action, and also (ii) at least one reactive, where appropriate hydrolyzable, silane compound, which is capable of reacting chemically in situ with the thermoset surface which forms during the molding process. The use of a mold-release agent of this type in a molding process and/or in a post-curing process for the production of thermoset moldings with a hydrophobicized surface, and also the moldings produced in this way.