Several models predict the reflectance of a rough metallic surface. They are however not adapted to the surfaces used in the packaging industry, such as boxes made of printed metallic plates. For printing purposes, metallic surfaces need to be varnished. Light reflection properties are therefore modified. We propose methods which adapt existing reflectance models to varnished surfaces. We also present a correction capable of predicting the reflectance even if incident light is not collimated, i.e. not composed of parallel rays.