The grey scale consists of nine pairs of non-glossy grey and white coloured chips which
illustrate the perceived depth of staining. These give a corresponding fastness
rating of 5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, 1.
They are used to assess the amount of staining occurring on adjacent undyed fabrics during fastness tests.
Their use is described in ISO 105-A03.