Silk is a natural protein fiber composed mainly of fibroin and is produced by certain insect larvae to form cocoons. Silk has a high emissivity for infrared light, making it feel cool to the touch. Even though silk has a small percentage of the global textile market, it is a multibillion-dollar trade. The unit price for raw silk is roughly twenty times that of raw cotton.
Acid dyes and pre-metallized dyes are used in dyeing of nylon which are water-soluble and dyed by ionic bonding. In the dyeing process, various dyeing auxiliaries such as levelling agents for level dyeing, soaping agents for washing off unfixed dyes for improving dye fastness, fixing agents for fixing dyes to fibers or fabric are used.