The Use of Airborne Ultrasonics for Generating Audible Sound Beams

The process of coating an organic polymeric shaped article with aluminum orthophosphate, using an anion compound as a source of aluminum, and topcoating with a polymer is further improved to enhance barrier properties under moist conditions. The aluminum orthophosphate coating is dried to effect no more than a partial cure and the anion concentration is reduced below about 1% of the weight of the solids content of the coating prior to completing the cure. The top-coating may be applied prior to completing the cure and then dried at a temperature to effect a substantially complete cure of the aluminum orthophosphate.