A method and apparatus providing a platen for supporting a media sheet. This activity is potentiated by the addition thereto of small amounts of a co-biocide for which the blend acts as a delivery system for the otherwise water-insoluble co-biocide. The incident light excites surface plasmons in the top metal surface layer and this energy couples through the apertures to the opposing surface where it is emitted as light from the apertures or from the rims of the apertures.