• Why does the fabric shrink?

Shrinkage is a phenomenon in which the length or width of textiles undergoes washing, dehydration, and drying in a certain state. The degree of shrinkage involves different types of fibers, fabric structure, different external forces experienced during fabric processing, etc., and has different performance.

• Reasons for 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, and the yarn fiber and the fabric structure generate internal stress, in the static dry relaxation state, Either in the static wet relaxation state, or in the dynamic wet relaxation state or fully relaxed state, the internal stress is released to varying degrees, so that the yarn fibers and fabrics return to their original state.

2. Different fibers and their fabrics have different degrees of shrinkage, which mainly depends on the characteristics of their fibers-hydrophilic fibers have a greater degree of shrinkage, such as cotton, hemp, viscose and other fibers; while hydrophobic fibers have shrinkage degrees Less, such as synthetic fibers.

3. When the fiber is in the wet state, the fiber will expand due to the action of the immersion liquid, which will increase the fiber diameter. For example, on the fabric, the fiber curvature radius at the interlacing point of the fabric is forced to increase, resulting in the shortening of the fabric length. For example, cotton fiber expands under the action of water, the cross-sectional area increases by 40-50%, and the length increases by 1-2%, while the synthetic fiber shrinks by heat, such as boiling water shrinkage, generally about 5%.

4. When the textile fiber is heated, the shape and size of the fiber will change and shrink, and it will not return to the original state after cooling down, which is called fiber thermal shrinkage.

• Factors that cause fabric shrinkage

1. Different fabric materials have different shrinkage rates.

2. Yarn (thread) is made up of fibers arranged by twisting the yarn axis.

3. The density of the fabric is different, and the shrinkage rate is also different.

4. Different fabric production processes have different shrinkage rates.

5. Washing care, including washing, drying, and ironing, each of these three steps will affect the shrinkage of the fabric.

• Shrinkage rate of general fabric

• “Shrinkage rate” is officially called “washed size change rate”, which refers to the percentage of textiles that shrink after washing or immersion in water.
  Shrinkage rate = (size before washing-size after washing) / size before washing × 100%
  Under normal circumstances
  Cotton 4%-10%;
  Cotton mercerized plain weave: shrinkage rate is 3.5% in warp direction and 3.5% in weft direction;Cotton mercerized twill: shrinkage rate of 4% in warp direction, 3% in weft direction;
  Cotton plain cloth: shrinkage rate is 6% in warp direction, 2.5% in weft direction;
  Cotton polyester 3.5%-5 5%;
  Chemical fiber 4%-8%;

• Hotel textile shrinkage rate

The shrinkage rate of hotel textiles can be referred to

GB/T 8628 Textiles Preparation, marking and measurement of fabric samples and clothing in the test for determining dimensional changes (GB/T 8628-2001, eqvISO3759:1994)
GB/T 8629 Textiles test household washing and drying procedures (GB/T 8629-2201, eqvISO6330:2000)
GB/T 8630 Textiles-Determination of dimensional change after washing and drying (GB/T 8630-2002, ISO 5077:1984, MOD)
GB/T 22800-2009 Star-rated tourist hotel textiles (picture below) 4.3.1 Intrinsic quality

There are also IWS TM31, BS 4923, EN25077/26330, JIS L1909 and so on. There are separate textile standards, such as GB/T 22864-2009 “Towels”, GB/T 22797-2009 “Sheets”… all can be used as reference.

The degree of fabric shrinkage is also a measure of product quality. The shrinkage rate directly affects the grading, plate making, cutting, sewing and washing in the later stage of production. And also affects the production cost and the difficulty of making it. It is an important criterion for measuring the quality of clothing (home textiles).

In view of the shrinkage rate, the national standards for textile products made clear provisions as early as 2004: the washing size change rate of superior textile products cannot exceed “2%~3%”. and the first-class products cannot exceed “2%~ 4%”, qualified products cannot exceed “2%~5%”.