It is an accelerated test to assess how efficiently the paint film protects the substrate against corrosion. Coated steel panels scribed through the coating, exposing the bare steel, are hung on in a 35ºC chamber by non-metal grids, where they are exposed to a continuous mist of 5% NaCl salt solution. For industrial coatings, after a test period of a few hundred hours to a few thousand hours, the panels are examined for degradation of the paint film and corrosion of the substrate.