Fabric shrinkage is a phenomenon in which the size or shape of a fabric changes during the washing or laundering process. Factors influencing fabric shrinkage include:

1. Influence of fibre composition

Different fibres and their fabrics, the degree of shrinkage are different, mainly depending on the hydrophilic properties of their fibres, i.e. moisture absorption properties. Moisture-absorbing fiber fabrics, fiber in the immersion of water will produce swelling, diameter increases, length shortens, shrinkage condition is obvious. For example, viscose fibres have a large water absorption rate, and fabrics with a large moisture absorption like these will produce severe shrinkage after washing. Synthetic fabrics, such as polyester and polypropylene, are less hygroscopic and therefore have a smaller rate of size change in the wash.

In addition, wool and other fibre fabrics with scale structures undergo felt shrinkage. Under the mechanical action of water, the one-way irreversible phase jamming of the wool scales causes continuous felt shrinkage of the wool fabric, which can be improved by both addition (closing the scale layer) and subtraction (removing the scale layer by chemical means).

2. Influence of the fabric structure

The fabric itself has a different structure and weaving tension, which results in different shrinkage rates and different shrinkage rates. Weaving tension is small, the fabric is tight and thick, the weaving shrinkage rate is large, the shrinkage rate of the fabric is small; weaving tension is large, the fabric is loose and thin, the weaving shrinkage rate is small, the shrinkage rate of the fabric is large.

The density of the fabric is different, the shrinkage rate is also different. Such as warp and weft density is similar, its warp and weft shrinkage rate is also close. The warp density of the fabric, the warp shrinkage is large, and vice versa, the weft density is greater than the weft density of the fabric, the weft shrinkage is also large.

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 ones. In woven fabrics, the general shrinkage rate of plain fabrics is less than flannel fabrics; and knitted fabrics, flat needle organization shrinkage rate is less than ribbed fabrics.

3. The influence of the production process

Generally speaking, fabrics are stretched by machines during the weaving and dyeing process and processed for a long time, so that tension exists on the fabric. However, the fabric is easily released from tension when exposed to water, so we will find the fabric shrinks after washing.

In addition, textile fibres are subjected to heat conditions, the form and size of the fibres change and shrink, and cannot return to their initial state after cooling down, known as thermal shrinkage of fibres. For example, the boiling water shrinkage rate of processing polyester staple fiber is 1%, vinylon boiling water shrinkage rate of 5%, chlorine spandex hot air shrinkage rate of 50%. Heat shrinkage, mainly in polyester nylon, a thermoplastic chemical fibre above, is improved by good heat setting during dyeing and finishing, making it possible to obtain good dimensional stability through high temperature setting.

In order to improve the problem of fabric shrinkage, the following measures can be used:

1. use high quality fibre raw materials, such as long-staple cotton, mulberry silk, etc., in order to improve the dimensional stability of the fabric.

2. Use a more compact fabric structure to reduce the amount of shrinkage of the fabric.

3. Control the water temperature and the amount of detergent used to avoid excessive shrinkage.

4. Adding shrinkage agents during the fabric production process to improve the dimensional stability of the fabric.

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