Abstract: The present invention relates to the use of paraffin waxes or microwaxes in silicone pastes, in particular in kneadable compositions for the production of accurate impressions of teeth. The silicone pastes are preferably cold-vulcanizing two-component silicone rubber systems which are known per se and in which two pastes are mixed and then crosslink after about 2-5 minutes at room temperature.

Abstract: In the making of a shaped structure by mixing(a) a cross-linkable organopolysiloxane,(b) hydrophobic filler particles,(c) paraffin oil,(d) a colorant, and(e) a cross-linking catalyst,the improvement which comprises employing as (b) hydrophobic filler particles of which the surface has been laden with 0.5-5% by weight of paraffin oil. The filler can be present in either or both of a cross-linkable silicone component and a catalyst component; each component can contain other ingredients but will not cure until the two components are brought together. Truer dental impressions are thereby formed.

Abstract: In a polysiloxane-based composition which crosslink by addition, comprising (a) an organosiloxane with two or more vinyl groups in the molecule, (b) and organo-hydridopolysiloxane, as a crosslinking agent, (c) a catalyst for accelerating the addition reaction, (d) a hydrophobic filler and (e) optionally a dyestuff pigment, the improvement which comprises (f) hydrogenated castor oil as a structuring agent. The composition is highly viscous and will not run but can readily be stirred.

Abstract: A process for producing an inorganic-organic composition material based on gypsum and polyurethane comprising exposing calcined gypsum or anhydrite to the action of water in the presence of a polyurethane or polyurethane-urea which is dispersible in water and in the presence of up to about 20% by weight (relative to the total mixture) of an alcohol and up to about 20% by weight (relative to the total mixture) of another organic solvent, and allowing the composition to set while permitting any solvents which may be present to evaporate. The calcium sulphate may be on a textile support or the composition may be molded into flexible shaped articles of good mechanical properties.

Abstract: Contact lenses and contact shells of light-refracting material consisting essentially of a copolymer of(I) from 40 to 90% by weight of methyl methacrylate and(II) from 10 to 60% by weight of methyl acrylate and/or esters corresponding to formula (1): ##STR1## in which R represents H or CH.sub.3,R' represents H, CH.sub.3 or C.sub.2 H.sub.5 andn=1 or 2,the sum of I and II amounting to 100% by weight.