Abstract: The present disclosure concerns specially patterned zinc sheets for coverage and protection of building roofs and facades. A recurrent problem linked with the use of zinc sheets in building applications is the development of white rust. As the complete avoidance of white rust is difficult to achieve, additional means to reduce its impact are most welcome. It is now proposed to limit the visibility of white rust by providing a camouflaging pattern on the surface of the zinc. The invention more specifically concerns an unweathered rolled zinc alloy sheet with at least one patterned face having an optical reflectivity that varies from region to region, characterized in that said regions are of a pseudo-random shape, having characteristic dimensions in the range of 0.1 mm to 10 cm; and in that the optical reflectivity, when measured across the sheet in any arbitrary direction, presents a specular reflectivity RMS deviation of more than 3 GU and/or a diffuse reflectivity RMS deviation of more than 0.2.