Why do denim desizing, washing and floating treatments?
Denim refers to twill weave, indigo-dyed denim, also called denim. In other words, all jeans are denim. All woven fabrics need desizing treatment, and denim is no exception. General woven fabrics will be desizing treatment during dyeing or printing. However, the early denim fabrics were woven directly after dyeing the yarn, without the process of dyeing or printing cloth. Therefore, the finished denim is not desizing, and it can only be desizing when washing.
The popular denim is mercerized and coated. Some have been desizing before processing, so desizing is not necessary. The color dyed on jeans is mainly indigo, which is a non-solid color. Indigo cannot be directly dissolved in water and cannot be dyed directly on cotton yarn. The purpose of dyeing can only be achieved by first oxidizing and then reducing. This determines that the indigo dyeing process cannot have a 100% dyeing rate. Will cause a lot of floating color. This part of the floating color is washed off by several clean water tanks before passing through the slurry tank during the dyeing process. But a lot of it remains on the yarn. Therefore, the finished fabric after weaving and finishing still contains a lot of floating color.
In addition to indigo, sulfur dyes are also useful, and they also have floating color. It is a very important job to wash off the floating color of jeans through the washing plant.
