Air Products Polymers, L.P. has introduced a new “Barrier Products Learning Center” at www.airproducts.com/FDAletters.      Barrier coatings are coatings or finishes that are applied to a surface to prevent penetration of liquids or gases from one side of the surface to the other. A barrier coating can either serve to protect or shield the encased material from substances which will alter the material’s properties, or it can prevent components of the encased material from migrating through and...