Disclosed is an aqueous acid solution or suspension of a preparation as well as the production thereof for the permanent finishing of fiber materials, especially dyed carpets, to render them antistatic, dirt-repellent and, optionally, antimicrobial, which aqueous preparation contains:A. 10 to 20 per cent by weight of at least one antistatic agent,B. 3 to 35 per cent by weight of a stabilized, aqueous non-film-forming dispersion of polystyrene,C. 1 to 6 per cent by weight of at least one acid, especially o-phosphoric acid, andD. 0 to 5 per cent by weight of further components, such as an antimicrobic agent and a solubility-promoting agent.