The barrier properties of a water soluble gas barrier material are
improved if the material is blended with a nanoparticle calcium carbonate
having a size of from 10 to 250 nanometers. The barrier material is on a
substrate to provide a substrate with gas barrier properties. A layer of
heat sealable material may be applied to the exposed surface of the
barrier material. A method for making the barrier coated substrate is
disclosed.