Carboxylic acid diesters are employed for treating, in particular for cleaning textile materials, and more particularly for removing paint stains from textile fibers to improve the cleaning thereof; the subject dicarboxylic acid diesters have the formula (I), R1—OOC-A-COO—R2, in which R1 and R2, which may be the same or different, are each a linear or branched, cyclic or non-cyclic C1-C20 alkyl, aryl, alkyaryl, or arylalkyl radical, and the group A represents a branched divalent C3-C10 alkylene radical.