The invention relates to a process for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic diluents or solvents, for the production of multicoat finishes, preferably metallic finishes. In the process according to the invention, up to 10% by weight of the components which are volatile under processing conditions, are replaced by an aliphatic polyether or by mixtures of aliphatic polyethers, the aliphatic polyethers having a mean molecular weight of not less than 300, containing not less than one hydroxyl group per molecule and being liquid under normal conditions.