Perspiration fastness shows whether a colour changes or transfers to other materials when the fabric is in contact with sweat. It is tested with artificial acid and alkaline solutions under ISO 105 E04, and graded from 1 to 5. It matters most for T-shirts, sports tops, uniforms and clothes worn directly on the skin.
Problems show up on dark or intense colours, as underarm marks or fading. Ask for the grade for both the acid and the alkaline solution. Grades of 4 or above are generally desired. On very dark shades, reading this together with wet rubbing gives the best picture of real-life behaviour.
perspiration fastnessiso 105sportswear