Abstract: A water-repellent plaster molding is produced by forming a foam of water, surfactant and polyalkyl-hydrogen-siloxane adding this foam to a paste of plaster powder in water, and letting the mixture set.

Abstract: A release agent for a polyurethane molding composition by weight comprising about 90 to 97 parts of an organic solvent and about 10 to 3 parts of a TiO group-containing polysiloxane.

Abstract: An aqueous alkylhydridopolysiloxane emulsion is stabilized against loss of hydrogen by addition thereto of about 0.1 to 5% by weight of an emulsifier containing perfluoroalkyl groups. The emulsion may further contain a fluoroalkyl-substituted siloxane of the formula ##STR1## wherein R each independently is alkyl with 1 to 6 carbon atoms or phenyl,R.sub.F is fluoroalkyl with 4-12 carbon atoms,a is about 5 to 70, andb is about 5 to 70.Advantageously the emulsifier is a member selected from the group consisting of a perfluoroalkyl ether of the formulaC.sub.x F.sub.2x+1 SO.sub.2 N (CH.sub.3) CO--(OCH.sub.2 --CH.sub.2).sub.n --(OCH CH.sub.3 CH.sub.2).sub.m --OC.sub.4 H.sub.9,whereinX=about 6-12,n=2-about 40 andm=2-about 40,and a perfluorinated alkane sulphonic acid salt of the formulaC.sub.x F.sub.2x+1 SO.sub.3 N(C.sub.n H.sub.2n+1).sub.4whereinx=6-12 andn=1-3.