Abstract: The present invention provides a curable aqueous composition comprising a (co)polymer and an epoxy crosslinker. The (co)polymer comprises, as (co)polymerized units, from 0.05% to 10% by dry weight, based on total monomers of the (co)polymer, ethylenically unsaturated acidic monomers having at least two carboxylic acid groups, and the epoxy crosslinker is an aliphatic compound having at least two reactive oxirane groups. It further provides a method for forming a treated substrate and a substrate formed by the method.