A method for increasing the scratch hardness of a body, which has at least in some regions a surface (4a) consisting of an extrudated or co-extrudated plastic (4), wherein an organic, fluoro-organic or silico-organic compound (18) that increases the scratch hardness is applied to the surface (4a) of the extrudated or co-extrudated plastic (4), wherein the organic, fluoro-organic or silico-organic compound (11a, 18) is applied to the surface (4a) of the extrudated or co-extrudated plastic (4) by means of a sheet-like transfer medium (6, 11), on which the organic, fluoro-organic or silico-organic compound (11a, 18) is disposed.