Using polymers with carboxyl groups in combination with divalent cations to form a protective layer

Agent for treating textile comprising a) polymers with carboxyl groups in a concentration of 1 to 10% by weight, preferably 2 to 4% by weight, b) divalent cations in a concentration of 0.001 to 1.0% by weight, wherein at least 20% of the monomeric units of the polymer carrying carboxyl groups, in the case the polymer is a polysaccharide and at least 20% of the monomeric units of the polysaccharide are uronic acids.