Agent comprises: at least 35 wt.% of one or more fatty alcohol sulfates (I)； at least a polyol, fatty acid alkylamide and/or betaine； and water. Agent comprises: at least 35 wt.% of one or more fatty alcohol sulfates of formula (R 1>；O-SO 3X) (I)； at least a polyol, fatty acid alkylamide and/or betaine； and water. R 1>；6-22C, preferably 12-18C-aliphatic alkyl and/or -alkenyl； and X : alkali- and/or alkaline earth-metal, ammonium, alkyl ammonium, alkanol ammonium or glucammonium. An independent claim is included for preparing a preparation containing at least 35 wt.% of (I), comprising continuously adding a mixture of water and polyol or oil soluble betaine to a non-neutralized (I) together with a quantity of alkali, where: the volume ratio of water to polyol or oil soluble betaine is 3:1-1:3； the quantity of alkali is selected in such a way that (I) is completely neutralized； and the mixing of the mixture with the non-neutralized (I) and alkali, is continued until at least a concentration of neutralized (I) is reached to 35 wt.%.
