Why does the fabric turn yellow?

Yellowing, especially the yellowing of white or light-colored elastic fabrics during finishing, storage and transportation is a major challenge faced by fabric finishers.

The yellowing problem may cause complaints and conflicts between the organizer and the clothing manufacturer or even the customer. In addition, finishing to avoid or eliminate fabric yellowing is time-consuming and costly. Therefore, this problem cannot be ignored.

Generally speaking, textile manufacturers must deal with yellowing caused by temperature and storage. But yellowing of elastic fabrics is a more complicated phenomenon that must be considered to be avoided. A certain degree of yellowing may be caused by fabric heat setting, contact heat forming, storage, heat setting and storage in nitrogen oxide compounds, and forming of foam-lined fabrics (such as women's corsets).

2. Hot yellowing

First, the grey fabric is heat-set on a gas stenter, and it is severely yellowed due to contact heat finishing (forming) and the bonding process. Elastic fabrics made of polyamide and more and more polyester are particularly sensitive. These problems become more serious when microfiber products exhibit their extremely large surface areas.

There are more and more problems caused by cotton/spandex blended knitted fabrics. Yellowing is prone to occur in the initial heat setting step to eliminate curling to obtain sufficient stable size. Usually the fabric will turn brown after finishing in this step, so it must be passed Time-consuming and costly scouring and bleaching process to achieve the required whiteness.

3. Yellowing caused by nitrogen oxides

The yellowing caused by nitrogen oxidation is affected by the fiber material used, and is similar to phenolic yellowing. When exposed to nitrogen oxide gas, during textile dyeing and finishing, elastic polyimide or polyester products, depending on their spandex content, show more or less a yellowish to reddish color change.