A composite sheet is manufactured by depositing a multi-layer coating on the outer surface of a substrate, the coating comprising a metal layer and an outer polymeric layer formed from a precursor comprising a composition capable of being polymerized and/or cross-linked by free-radical processes. After the precursor is applied, the composite sheet is exposed to beam radiation and ozone, which both promote conversion of the precursor. The function of the cured polymeric layer includes protecting the metal layer from corrosion. The use of both beam radiation and ozone promotes substantially full conversion and curing of the precursor, even in portions of the substrate that are geometrically shadowed from incident beam radiation.