This document (EN ISO 105-E05:2010) has been prepared by Technical Committee ISO/TC 38 "Textiles", in collaboration with Technical Committee CEN/TC 248 "Textiles and textile products", the secretariat of which is held by the BSI (United Kingdom). The responsible German Committee is NA 062-05-11 AA "Farbechtheit von Textilien - Deutsche Echtheitskommission DEK" ("Colour Fastness of Textiles - German Colour Fastness Committee") at DIN. This part of ISO 105 specifies a method for determining the resistance of the colour of textiles of all kinds, and in all forms, to the action of dilute solutions of organic and mineral acids. Four tests differing in severity are provided. Any or all can be used, depending upon the nature of the fibre. A few drops of the acid solution are placed on a specimen of the textile material to be tested by rubbing the acid solution gently into the material with a glass rod. The change in colour of the textile, while it is still wet and after drying, shall be assessed either visually or instrumentally.