What are the reasons that affect the shrinkage rate?

1. Raw materials

The raw material of the fabric is different, and the shrinkage rate is different. Generally speaking, fibers with high hygroscopicity will expand after soaking in water, their diameter will increase, and their length will shorten, and their shrinkage rate will be large. If some viscose fibers have a water absorption rate of up to 13%, while the synthetic fiber fabrics have poor moisture absorption, their shrinkage rate is small.

2. Density

The density of the fabric is different, and the shrinkage rate is also different. If the warp and weft densities are similar, the warp and weft shrinkage rates are also similar. The fabric with high warp density will shrink greatly in the warp direction. On the contrary, if the weft density is greater than that in the warp density, the shrinkage in the weft direction will be large.

3. Yarn thickness

The thickness of the yarn count of the fabric is different, and the shrinkage rate is also different. Fabrics with coarse yarn counts have higher shrinkage rates, while fabrics with fine yarn counts have lower shrinkage rates.

4. Production process

Different fabric production processes have different shrinkage rates. Generally speaking, in the process of weaving and dyeing and finishing of fabrics, the fibers need to be stretched many times, the processing time is long, and the shrinkage of the fabric with greater tension is greater, and vice versa.

5. Fiber composition

Compared with synthetic fibers (such as polyester and acrylic), natural plant fibers (such as cotton, hemp) and plant regenerated fibers (such as viscose) are easy to absorb moisture and expand, so the shrinkage rate is larger, while wool is due to the scale structure on the surface of the fiber. And it is easy to felt, which affects its dimensional stability.

6. Fabric structure

In general, the dimensional stability of woven fabrics is better than that of knitted fabrics; the dimensional stability of high-density fabrics is better than that of low-density fabrics. In woven fabrics, the shrinkage rate of plain weave fabrics is generally smaller than that of flannel fabrics; and in knitted fabrics, the shrinkage rate of plain knitted fabrics is smaller than that of rib fabrics.

7. Production and processing process

Because the fabric is inevitably stretched by the machine in the process of dyeing, printing and finishing, there is tension on the fabric. However, the fabric is easily de-tensioned when exposed to water, so we will find that the fabric shrinks after washing. In the actual process, we generally use pre-shrinking to solve this problem.

8. Washing and nursing process

Laundry care includes washing, drying, and ironing, each of which affects the shrinkage of fabrics. For example, the dimensional stability of hand-washed samples is better than that of machine-washed samples, and the washing temperature also affects its dimensional stability. In general, the higher the temperature, the worse the stability. The drying method of the sample also has a great influence on the shrinkage of the fabric.

Commonly used drying methods include drip drying, metal mesh tiling, hanging drying and tumble drying. Among them, the drip drying method has the least effect on the size of the fabric, while the drum drying method has the greatest effect on the size of the fabric, and the other two are in the middle.

In addition, choosing a suitable ironing temperature according to the composition of the fabric can also improve the shrinkage of the fabric. For example, cotton and linen fabrics can be ironed at high temperatures to improve their dimensional shrinkage. But it is not the higher the temperature, the better. For synthetic fibers, high-temperature ironing will not only improve its shrinkage rate, but will damage its performance, such as the fabric being hard and brittle.