The textile sector, whether in the world or in our country, is the oldest and most common industry branch. In the textile industry, all fibers, natural or synthetic or regenerated fibers and their blends undergo many processes from fiber to a textile product. It is inevitable to use some chemicals as input in these stages. It is also a fact that these chemicals are large in both quantity and variety.

Chemicals are preferred to facilitate processing in all processes applied to textile products. During the production of textile products, auxiliary chemicals are used in all processes, from the preparation of yarns to the garments, to facilitate the processes, to make them more effective or to achieve a certain effect on the products.

Substances referred to as chemicals are generally organic and inorganic acids, bases, salts and the like. The chemical structure of these substances is evident. However, auxiliary chemicals are substances specially developed for textile products and whose chemical structures are reserved for commercial purposes. However, all these chemicals and auxiliary chemicals have positive and negative effects on the fastness of the resulting product.

Light fastness is the most remarkable among these fastness values. In recent years, although light fastness studies have been carried out under artificial lights such as quartz lamps, it is essential to determine the light fastness of these assessments in natural conditions.

A blue scale is used to assess light fastness. The light fastness values ​​on this scale range from 1 to 8. As this value approaches 8, light fastness is excellent.

The fastness of light in textile products to determine the negative effects of daylight on fabrics is determined in accordance with the following standard:

• TS EN ISO 105-B02 Textile - Color fastness tests - Part B02: Determination of color fastness to artificial light - Xenon arc fading lamp test