Creases appear on the fabric! What is the reason?

Mechanism of creases
1. Cotton knitted scalding, bleaching and dyeing are generally carried out in overflow tanks. The fabric remains in a rope-like state during the entire process. The fiber is constantly bent and deformed in the dyeing machine, the original hydrogen bonds are constantly destroyed, and new hydrogen bonds are constantly formed. Sometimes the newly formed hydrogen bonds cannot be completely restored, so chicken claw marks and dead creases are formed on the surface of the fabric.
2. In the single-sided fabric structure, the tension of the yarns on both sides is asymmetric, and the fabric is difficult to recover after being wrinkled in one direction for a long time. Therefore, among various structures, plain weave, sweatshirts, etc. are more likely to have crease problems, especially concentrated on fabrics with less or larger weight. The generation of creases is also closely related to yarn count and twist. The finer the yarn count and the higher the twist, the greater the possibility of reverse untwisting of the yarn, and the more likely it is to have crease problems.
The main process steps for creases - boiling and bleaching
1. The general dyeing and finishing process is: prepare the cloth → sew the ends → put it into the vat for boiling and bleaching → dyeing → soaping → fixation → softening → take it out of the vat → dehydration → drying the cloth with a vibration machine or a dryer. Generally, many people think that creases are mainly formed in the dyeing vat, but our engineers have verified through rigorous experiments that in fact, most cotton knitwear has formed creases in the boiling and bleaching stage, but it is not easy to observe before dyeing.
2. Fabrics and equipment that are prone to creases during the bleaching stage include the following:
Fabric reasons: Single-sided cotton fabrics with less or greater weight (e.g., weight <150g or >300g), especially cotton stretch fabrics (with spandex);
Equipment reasons: Compared with the L-type overflow cylinder, the J-type overflow cylinder is more prone to creases due to its strong tensile force; and the air flow cylinder is less likely to crease, because the fabric is fully blown open by high-pressure gas at the nozzle, and the fiber gets a "rest" from the tense state, which is conducive to the elimination of internal stress to reduce the crease problem;
Process reasons: Fabrics that have not been pre-shaped are more likely to have crease problems; Fabrics are shaped under high temperature, which can improve fiber proximity and orientation, and the fiber morphology is fixed, reducing the chance of changes in the dyeing tank, which is conducive to reducing creases.