An Ultimate Guide to Fabric Shrinkage

If you work in an apparel factory or a textile fabric development laboratory, read this blog about fabric shrinkage! This article helps you fully understand the causes of shrinkage and the influencing factors. You can learn to calculate the shrinkage results using formulas before mass production. It allows you to estimate the finished product’s shrinkage rate and avoid complaints that could harm your brand’s reputation when customers find clothes shrink after wash.

What Is Fabric Shrinkage?

Fabric shrinkage refers to the phenomenon where textiles change in length or width after undergoing processes like washing, dehydration, and drying. The difference in the length of the fabric before and after water immersion, expressed as a percentage of its original length, is known as the shrinkage rate. The stronger the water absorption capacity, the more intense the swelling, leading to a higher shrinkage rate and poorer dimensional fabric stability.

fabric shrinkage after wash

Why does fabric or cloths shrink?

Fabric shrinkage occurs primarily due to the accelerated recovery of the viscoelastic deformation of fibers and yarns when they absorb moisture. When fabric is soaked or washed, fibers absorb water, causing volume expansion, which increases the diameter of the fibers and thickens the yarn. The increased curvature of the yarn within the fabric forces it to contract.

Additionally, during the textile dyeing and finishing process, fibers and yarns are repeatedly stretched, accumulating residual deformation and significant stress. When water molecules penetrate the fibers, they reduce the interaction force between the large molecules of the fiber, leading to the recovery of viscoelastic deformation.

The greater the hygroscopicity and the swelling rate of the fiber, the higher the shrinkage rate of the fabric. Cotton, linen, wool, silk, and particularly viscose fibers, have high hygroscopicity, hence these fabrics have a higher shrinkage rate. The shrinkage of fabrics made of natural and regenerated fibers with good hygroscopicity is also due to the significant expansion in diameter of one system of yarns after absorbing moisture, which compresses the other system of yarns, causing them to bend more and leading to a noticeable shortening of the fabric in that direction. When the fabric dries, although the diameter of the yarns decreases, the surface tangential sliding resistance of the yarns limits their free movement, preventing the yarns from returning to their original state.

Synthetic fibers have poor hygroscopicity, and some almost do not absorb moisture, so the shrinkage rate of synthetic fiber fabrics is very low.

Factors of fabric shrinkage

Raw Materials: The shrinkage rate of fabric depends on its raw materials. Fibers that absorb more moisture, like some types of viscose fibers with up to 13% water absorption, swell up when wet, leading to higher shrinkage rates. Synthetic fiber fabrics, with poor moisture absorption, shrink less.

Density: The density of the fabric also affects shrinkage. Fabrics with similar density in warp and weft directions tend to have similar shrinkage rates. Fabrics with a higher warp density shrink more in the warp direction, and those with higher weft density shrink more in the weft direction.

Yarn Thickness: The thickness of the yarns in the fabric influences shrinkage. Fabrics with thicker yarns tend to have higher shrinkage rates, while those with finer yarns shrink less.

Production Process: Different manufacturing processes lead to different shrinkage rates. Generally, fabrics that are stretched more during weaving and dyeing, and those processed for longer times with greater tension, have higher shrinkage rates.

Fiber Composition: Natural plant fibers (like cotton and linen) and regenerated plant fibers (like viscose) absorb moisture and swell more easily than synthetic fibers (like polyester and acrylic), leading to greater shrinkage. Wool, due to the scale structure of its fibers, tends to felt, affecting its dimensional stability.

Fabric Structure: Woven fabrics generally have better dimensional stability than knitted fabrics. High-density fabrics are more stable than low-density ones. In woven fabrics, plain weave usually shrinks less than flannel, and in knitted fabrics, plain knit shrinks less than rib knit.

Manufacturing Process: During dyeing, printing, and finishing, fabrics inevitably stretch due to machine tension. This tension is released when the fabric encounters water, leading to shrinkage after washing. Pre-shrinking is a common industrial solution to address this issue.

Which fabrics shrink?

You may have questions like: Does linen shrink more than cotton? Will 100 percent cotton shrink? Does viscose material shrink? “The fabrics with the smallest shrinkage rate are synthetic fibers and blended fabrics, followed by wool fabrics and linen fabrics, with cotton fabrics in the middle. Silk fabrics shrink considerably, but the largest shrinkage occurs in viscose fibers, artificial cotton, and artificial wool fabrics.”

  • Cotton: 4% to 10%
  • Synthetic fibers: 4% to 8%
  • Cotton-polyester blend: 3.5% to 5.5%
  • Natural white fabric: 3%
  • Gabardine: 3% to 4.5%
  • Twill fabric: 4%
  • Workwear fabric: 10%
  • Artificial cotton: 10%

Standards for fabric shrinkage testing

There are several international standards for testing fabric shrinkage:

  • AATCC 135
  • AATCC 158
  • ISO 3759

These tests can be conducted at an authorized laboratory in a factory. Alternatively, they can take place at a third-party lab, like SGS or Intertek.

How to do a fabric shrinkage test

To address fabric shrinkage, common inspection methods include dry steaming and washing. For example, in a wash test, the process and method for testing shrinkage rate are as follows:

Sampling:

Take a sample from the same batch of fabric, at least 5 meters from the start of the roll.
The chosen fabric sample should not have any defects that could affect the results.
The sample should be cut to a size suitable for washing, typically a square measuring between 70 cm and 80 cm.
Lay the sample flat for 3 hours, then place a 50 cm x 50 cm sample in the middle of the fabric, and draw lines around its edges with a chalk pen.
Marking:

Place the sample on a flat surface, smoothing out any creases or uneven areas without stretching it.
When drawing lines, apply minimal pressure to avoid displacing the fabric.
Washing the Sample:

To prevent the lines from fading after washing, the sample needs to be stitched (double-layer for knit fabric and single-layer for woven fabric).
For knit fabric, stitch only the two sides in the warp direction and one side in the weft direction. For woven fabric, stitch all four sides.
The stitching should be neither too tight nor too loose. For coarse or easily frayed fabrics, use a three-thread overlock stitch on all four sides.
After stitching, place the sample in 30°C warm water, wash it in a washing machine, and then dry it using a dryer or by air-drying.
After 30 minutes of cooling, proceed with the actual measurement.
Calculation:

How to calculate fabric shrinkage?

Fabric Shrinkage = (Original Size – Final Size) / Original Size, then multiply by 100 to get the percentage.
Shrinkage should be calculated from both the warp and the weft perspectives.

Suppose a fabric sample has a warp length of 22 cm. Two warp yarns are removed from the sample, and upon straightening and measuring, one yarn measures 23.4 cm and the other measures 23.6 cm. To calculate the warp shrinkage rate of the fabric sample (for more accurate calculations, a larger number of yarns, typically around 10, can be used), use the formula:

warp yarn shrinkage rate calculate

warp formula

a – Warp shrinkage rate

L1 – Length of the warp yarn after straightening (i.e., the original length)

L2 – Length of the warp yarn in the fabric sample

Given the data, the warp shrinkage rate of this fabric sample is 6.38%.

Another example: The weft direction length of the fabric sample is 25.5 cm. Two weft yarns are removed from the sample and measured after straightening. One measures 27 cm and the other 27.2 cm. Calculate the weft shrinkage rate of the fabric sample using the formula:

weft yarn shrinkage rate calculate weft shrinkage formula

 

 

 

 

 

 

 

 

 

 

b – Weft shrinkage rate;

L3 – Length of the weft yarn after straightening;

L4 – Length of the weft yarn in the fabric sample.

The weft shrinkage rate of this fabric sample is 5.9%.

How to prevent fabric shrinkage?

The main methods for preventing shrinkage in fabrics include:

Minimize tension during the production process to avoid plastic deformation in a wet state. This involves reducing the elongation of the fabric under tension in various stages, such as weaving and dyeing and finishing processes.
Use loose drying to bring the fabric closer to a fully balanced state. Loose drying refers to keeping the fabric in a relaxed state during the drying process to reduce the impact of tension.
Perform mechanical preshrinking. Mechanical preshrinking uses specialized equipment to pre-shrink the fabric, reducing the rate of shrinkage during subsequent use.

Additionally, the following measures can be taken to reduce the shrinkage rate of fabric:

  • Reduce tension throughout the bleaching process.
  • Apply loose tension during wet fabric drying in the dyeing and finishing process to reduce elongation and prevent excessive narrowing of the width.
  • Control the tension during the mercerizing process to maintain the effective width of natural cotton fabric and carefully manage the tension in the weft direction.
  • Strengthen inspection of the mercerizing process conditions.
  • Perform preshrinking treatments for fabrics with high longitudinal shrinkage rates.
  • Ensure that the effective width of fabric is met for varieties with high transverse shrinkage rates.
  • Resin finishing or PU coating can reduce the shrinkage rate.
  • For T/C blended synthetic fabrics, properly manage the mercerizing process and operations to better control shrinkage rates.
  • The selection of specific measures should be based on a comprehensive consideration of the type of fabric, fiber composition, weaving structure, and other factors.

Why DaRong Shrinkage Testing Machine 089E?

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FAQ:

Q: Does the drying method of the sample affect shrinkage?
A: The drying method of the sample significantly impacts the shrinkage rate of the fabric. Common drying methods include drip drying, metal net laying, hang drying, and tumble drying. Among these, drip drying has the least impact on fabric dimensions, while tumble drying has the most significant impact, with the other two methods falling in between.

Q: How can the fabric shrinkage rate be reduced during dyeing and finishing processing?
A: In dyeing and finishing processing, preshrinking is commonly used to increase the weft density, pre-emptively enhancing the shrinkage rate, and thereby reducing the overall shrinkage rate of the fabric. It’s important to note that undergoing preshrinking does not mean the fabric won’t shrink; rather, it means that the shrinkage rate is controlled within the national standard of 3% to 4%. Underwear materials, especially natural fibers, are likely to shrink.

Q: What are the characteristics of wool fabric shrinkage rates?
The yarn twist, fabric structure, and dyeing and finishing processes of wool fabrics also affect their shrinkage rates. Fabrics with higher twist, tighter structure, good setting, and those treated with resin and anti-shrinkage processes have lower shrinkage rates. Woven fabrics shrink less than knitted fabrics. It’s important to note that when the warp and weft tightness of fabric varies, the shrinkage rate will differ accordingly.

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