The invention concerns a coating agent for cellulose-bearing substrate
surfaces comprising a liquid phase and binding agent, wherein the coating
agent includes platelet-shaped pigments and a bonding agent, wherein the
platelet-shaped pigments are corrosion-resistant and impermeable to UV
light and wherein the bonding agent produces a bond between pigment,
binding agent and the cellulose-bearing substrate surface. The invention
further concerns the use of the coating agent according to the invention
as well as coated cellulose-bearing substrate surfaces.