Colour fastness is a term used in the dyeing of textile materials, meaning resistance of the material's colour to fading or running. The term is usually used in the context of clothes. The first known use of the word colorfast was in 1916. In general, clothing should be tested for colourfastness before using bleach or other cleaning products. Light fastness, wash fastness, and rub fastness are the main forms of colour fastness that are standardized.
The light fastness of textile dye is categorised from one to eight and the wash fastness from one to five. The higher the number the better fastness is obtained.