The present invention is directed to mold release compositions based on a solution which is liquid at room temperature and contains(i) at least one zinc salt of a straight or branched chain, saturated or unsaturated aliphatic carboxylic acid containing 8 to 24 carbon atoms in(ii) at least one organic compound containing tertiary nitrogen atoms which is liquid at room temperature,the zinc salt being present in a quantity of about 10 to 75% by weight, based on the total weight of the composition, characterized in that component (ii) is based on at least one compound corresponding to the formula ##STR1## wherein R', R", R"' and R.sup.iv, which may be identical or different, denote alkyl group containing 1 to 4 carbon atoms or any two of the groups R' and R" or R"' and R.sup.iv may combine with the nitrogen atom to form a 6-membered heterocyclic ring optionally containing an oxygen atom or an alkyl substituted nitrogen atom as hetero atom and having a total of 4 or 5 carbon atoms,R denotes hydrogen or a group of the formula--(CH.sub.2).sub.o --NH.sub.2 andm, n and o denote identical or different integers with values from 2 to 6.The present invention is also directed to a mixture suitable for use as a reactant for polyisocyanates containing isocyanate-reactive groups and the mold release composition described above. Finally, the present invention is directed to a process for the production of a elastomeric molded article having a nonporous surface by reacting a polyisocyanate with the previously described mixture containing isocyanate-reactive groups and to the molded articles produced by the process.