Abstract: The invention relates to a composite sheet. Provision is made for the composite sheet to comprise a polymeric base sheet and a polymeric varnish layer, said varnish layer having an abrasion resistance, expressed as pencil hardness, of at least 4H; and a flexibility such that, when the composite sheet is bent around the two closely adjacent edges of a metal strip 100 ?m thick, the varnish layer does not break or delaminate from the base sheet; and said varnish layer having the following optical properties: a transmittance at 400, 600 and 800 nm of at least 85%, determined by applying the varnish layer-forming formulation with a thickness of 5 ?m to a slide, curing the varnish layer and determining the transparency of the slide with the varnish layer in comparison to an uncoated slide; and a turbidity of not more than 5%, determined by haze measurement.