Abstract: Disclosed herein is a barrier layer comprising a polyvinyl amine-polyvinyl alcohol copolymer applied to a substrate as a water-soluble composition, wherein the polyvinyl amine-polyvinyl alcohol copolymer is formed by copolymerizing: (a) from 99 to 1 mol % of N-vinylformamide and (b) from 1 to 99 mol % of one or more vinyl Ci-Ci0 alkyl esters, and then hydrolyzing from 30 to 100 mol % of the formyl groups from the copolymerized units (a) to form amino groups and from 30 to 100 mol % of the Cj-Cio alkyl ester groups from the copolymerized units (b) to form hydroxyl groups, wherein the copolymer has a unimodal compositional distribution as evidenced by essentially one peak in a gel permeation gradient elution chromatographic analysis. A method of producing a barrier layer is also disclosed.