Effect of Carpet Washing Chemicals on the Color Quality of Silk Yarns

In the carpet washing workshops, different chemicals are used in order to increase shine in the appearance of the carpet, soften the colors or remove the dye bleeding commonly. This method is known as gold or trade washing process. Due to the great variety of materials used in the process of gold or trade washing and on the other hand dyes with different chemical structure, the effect of different chemicals should be studied according to the structure of dyes. With research and study, suitable chemicals (remove bleeding materials) can be used to have the best result from the gold-washing process. Since silk yarns are used in luxury and high value-added hand-woven carpets, it will be very useful to have the knowledge of using the appropriate chemicals with the least damage on these yarns. In this research, after field studies, the procedure of gold washing that are used in hand-woven carpet washing workshops was identified. Among the common methods that were proposed, two methods were selected for application on silk yarns. Due to the importance of natural dyes, silk yarns were dyed with madder as a popular natural dye in different concentrations and pH of dyeing bath, after that exposed to two methods of gold washing. The color parameters and general fastness of the samples were measured and studied. The results showed that the chemicals used in gold washing affect the color shade of the samples. Color change varied according to the concentration of dye, dyeing method and also the concentration of applied chemicals.