Determination of wet fastness and colour resistance to repeated washings of reactive dyes depending on chromophore group

Abstract

The resistance of colour to repeated domestic washing is a critical performance requirement for cotton fabrics dyed with reactive dyes, particularly in terms of maintaining acceptable wet fastness and colour stability. Although the washing fastness of reactive dyed products is generally good, colour change remains an inevitable issue, particularly under repeated washing conditions. Within the scope of this study, this research aimed to determine how wet fastness values, and especially colour change after repeated washes, are influenced by the dye chromophore group, which is the primary colour-determining component of reactive dyes. The results demonstrated that monoazo, metal azo and anthraquinone-based dyes exhibited lower levels of colour change after repeated washes, whereas other dyes (phthalocyanine, copper formazan, bisazo and triphendioxazine) showed more pronounced colour changes. Regarding the effect of washing frequency, the colour differences observed between 0-1-5-10-20 washes and between 20-30-40-50-60 washes were found to be statistically insignificant. These findings indicate that colour loss remains at acceptable levels up to the first 20 washes, while substantial colour loss occurs after approximately 30 washes, depending on the dye type.