Why Does The Fabric Shrinkage Happen?
Shrinkage is a phenomenon that the length or width of textiles changes in a certain state after washing, dehydration, drying and other processes. Shrinkage degree involves different kinds of fibers, fabric structure, different external forces during fabric processing and so on.
The shrinkage of synthetic fiber and blended fabric is the smallest, followed by wool, hemp and cotton fabric. The shrinkage of silk fabric is larger, while the shrinkage of viscose fiber, artificial cotton and artificial wool fabric is the largest. Objectively speaking, all cotton fabric has the problem of shrinkage and fading, the key is the finishing.
Causes of Fabric Shrinkage
1. When the fiber is spinning, or when the yarn is weaving, dyeing and finishing, the yarn fiber in the fabric is stretched or deformed by external force. At the same time, the yarn fiber and fabric structure produce internal stress. In static dry relaxation state, static wet relaxation state, dynamic wet relaxation state and full relaxation state, the internal stress is released in different degrees, Return the yarn, fiber and fabric to their original state.
2. The degree of shrinkage of different fibers and fabrics is different, which mainly depends on the characteristics of the fibers – hydrophilic fibers, such as cotton, hemp, viscose, etc; However, hydrophobic fibers have less shrinkage, such as synthetic fibers.
3. When the fiber is wet, it will swell under the action of the soaking solution, which will make the fiber diameter larger. For example, on the fabric, it will force the curvature radius of the fiber at the interweaving point of the fabric to increase, resulting in the shortening of the fabric length. For example, the cross-sectional area of cotton fiber is increased by 40-50% and the length is increased by 1-2% under the action of water, while the heat shrinkage of synthetic fiber, such as boiling water shrinkage, is generally about 5%.
4. When textile fiber is heated, its shape and size change and shrink, and it can not return to its original state after cooling, which is called fiber thermal shrinkage. The percentage of length before and after thermal shrinkage is called thermal shrinkage, which is generally measured by boiling water shrinkage test. In 100 ℃ boiling water, the percentage of fiber length shrinkage is expressed; The percentage of shrinkage can also be measured in hot air over 100 ℃ and in steam over 100 ℃. For example, the shrinkage of PET staple fiber in boiling water is 1%, that of vinylon fiber in boiling water is 5%, and that of chloro fiber in hot air is 50%. Fiber is closely related to textile processing and dimensional stability of fabric, which provides some basis for the design of post process.
Factors of Fabric Shrinkage
1. Fabric shrinkage is different with different raw materials. Generally speaking, the fiber with high hygroscopicity will expand, increase in diameter and shorten in length after soaking, resulting in large shrinkage. For example, the water absorption of some viscose fiber is as high as 13%, while the moisture absorption of synthetic fiber fabric is poor, and its shrinkage is small.
2. Yarn (thread) is made up of fibers arranged by twisting and winding the yarn axis. Its size change in water is not only related to the nature of the fiber, but also related to its structure, such as twist and tightness. Generally speaking, the shrinkage of fabric is different with different count thickness. The shrinkage of coarse yarn is larger than that of fine yarn.
3. The shrinkage of fabric is different with different density. If the density in longitude and latitude is similar, the shrinkage in longitude and latitude is also similar. If the warp density is large, the warp shrinkage will be large; otherwise, if the weft density is larger than the warp density, the weft shrinkage will be large. In general, the dimensional stability of high density fabric is better than that of low density fabric.
4. Fabric shrinkage is different with different production process. Generally speaking, in the process of weaving, dyeing and finishing, the fiber needs to be stretched many times, the processing time is long, and the shrinkage of the fabric with larger tension is larger, otherwise it is smaller. In order to control the width of cloth, in the actual process, we usually use pre shrinkage to solve this problem.
5. Washing care, including washing, drying, ironing, each of these three steps will affect the shrinkage of the fabric. For example, the dimensional stability of hand washing is better than that of machine washing, and the washing temperature will also affect its dimensional stability. Generally speaking, the higher the temperature, the worse the stability.
Choosing an appropriate ironing temperature according to the fabric composition can also improve the shrinkage of the fabric. For example, cotton and linen fabrics can be ironed at high temperature to improve their dimensional shrinkage. But the higher the temperature, the better. For synthetic fiber, high temperature ironing can not improve its shrinkage, but will damage its properties, such as hard and brittle fabric.
Shrinkage of General Fabrics
The formal term “shrinkage” is “washing dimensional change rate”, which refers to the shrinkage percentage of textiles after washing or soaking.
Shrinkage = (size before washing – size after washing) / size before washing × 100%
The Common Fabric Shrinkage Chart
Cotton fabric shrinkage: 4% – 10%;
Cotton mercerized plain fabric: shrinkage 3.5% in warp and 3.5% in weft;
4% for twill;
Cotton mercerized twill fabric: shrinkage 4% in warp and 3% in weft;
Cotton plain fabric: shrinkage 6% in warp and 2.5% in weft;
Cotton polyester fabric shrinkage: 3.5% – 5.5%;
Polyester fabric shrinkage: 4% – 8%;
Hope you had a general idea about why and how does the fabric shrinkage, the causes and factors. Comment below for what you want us to share and we’ll glad to do that so. Have a nice day!