Textiles — Tests for colour fastness — Part G04: Colour fastness to oxides of nitrogen in the atmosphere at high humidities

A test specimen and a apiece of control fabric are simultaneously exposed to oxides of nitrogen in an atmosphere which is maintained at 87.5 % 2.5 % relative humidity and at temperature of 40 °C 1 °C until the control fabric shows a colour change corresponding to that of a reference of fading. The exposure/measurement cycle is repeated until the specimen shows a definite colour change or for a prescribed number of cycles.