the present invention relates to compositions which are suitable for optimizing mineral building material compositions so that the flow behaviour and the deaeration of the compositions is positively influenced , as a result of which very smooth , virtually pore - free surfaces can be achieved . the compositions can consist of a mixture or comprise a mixture which contains at least one component which comprises a compound n which displays a wetting action in aqueous cement - containing binder systems and contains at least one further component which comprises a compound e which has antifoam properties in aqueous cement - containing binder systems . the compound n in component a ) can preferably be a nonionic or amphoteric surfactant , preferably an alkyl alkoxylate or a betaine . the compound e in component b ) can preferably be a polyetherpolysiloxane on a support material .