Foil as covering for an impression cylinder of a sheet-fed offset rotary perfecting press

The invention relates to a foil (1) as a dressing for a back pressure cylinder (9) of a sheet-fed offset rotary perfecting press, which dressing consists of a non-resilient, chemically resistant and wear-resistant substrate layer with good ink transfer characteristics and with a surface with a ball-shaped structure with statistically evenly distributed convex (2) and concave (6) structure elements and of a chromium layer which is located on said structure elements, forms the sheet-conveying outer surface of the back pressure cylinder and reduces the micro-roughness, the sheet being supported on the poles (4) of the convex (2) structure elements. These convex (2) structure elements have an oval shape (7) with a radius of curvature which increases from the pole (4) to the transition (5) into the concave (6) structure elements.