An especially effective hydrophilicizing treatment for solid surfaces, particularly those of conversion coated aluminum, is a liquid mixture of water, organic polymer molecules that include sulfonyl/ate moieties, and preferably also a substance made by mixing with aqueous phosphoric acid at least one metal, metal oxide, or metal hydroxide so as to form a transparent liquid mixture. The treatment liquid preferably has a nearly neutral pH and is applied to a substrate and dried in place by exposure to heat.