Textile hydrostatic pressure refers to the resistance encountered when the water penetrates the fabric. Under…
This article is developed from four aspects: the basics of fabric shrinkage (definition, principle, common sense), the factors affecting fabric shrinkage, the test method of fabric shrinkage, and how to textile fabric shrinkage during the washing and care process. This should be the most comprehensive guide on fabric shrinkage.
Table of Contents
The Basics of Fabric Shrinkage
1 What is the fabric shrinkage?
Fabric shrinkage is a textile in a certain state, after washing, dewatering, drying and other processes, the length or width of a change in a phenomenon. Measure the degree of shrinkage index called shrinkage rate or shrinkage, the type of fiber, the structure of the fabric, weaving and processing of external forces, etc. will affect the shrinkage performance of the fabric.
2 The principle of fabric shrinkage
After the fiber absorbs moisture, its longitudinal and transverse are to swell, the volume increases, of which the transverse expansion is large and the longitudinal expansion is small. Therefore, after the fabric absorbs water, the diameter of the yarn will become thicker, thus causing the fabric to shrink. And because of the hysteresis of fiber moisture absorption, the fabric will maintain the contraction state after the impregnation and washing.
Note: Wool fabrics hardly shrink, but wet swell. This is because the curl of wool stretches and flattens when it absorbs moisture. Although the diameter of the fiber becomes thicker when it absorbs moisture, it is not as much as the growth of wool stretching. In addition, wool fibers in the washing will occur to the root of the moving interpenetrating felt shrinkage, which makes the yarn longer, so wool fabric performance is wet swelling.
3 The common sense of fabric shrinkage
The shrinkage rate of the smallest textile is synthetic and mixed textiles, followed by woolen fabrics, hemp fabrics, cotton fabrics in the middle, silk fabrics shrinkage is larger, and the largest is viscose fiber, rayon, artificial wool fabrics.
Objectively speaking, cotton fabrics are more or less shrinkage and fading problems, the key is the finishing behind. So the general home textile fabrics are pre-shrinking treatment. It is worth noting that after pre-shrinking treatment is not the same as no shrinkage, but refers to the shrinkage rate is controlled within 3% to 4%, lingerie material, especially natural fiber clothing will shrinkage.
Therefore, in the purchase of clothing materials, in addition to the quality of the fabric, color, pattern selection, the shrinkage rate of the fabric should also be understood. The following are the shrinkage rates of some common fabrics.
- cotton 4% to 10%;
- chemical fiber 4% to 8%;
- cotton polyester 3.5% to 5 5%;
- native white cloth for 3%;
- wool blue cloth 3% to 4%;
- poplin 3-4.5%;
- flower cloth 3% to 3.5%;
- twill cloth 4%;
- labor cloth 10%;
- rayon 10%.
The Influencing Factors of Fabric Shrinkage
According to the basics of fabric shrinkage, it can be seen that the influencing factors of fabric shrinkage are mainly related to the types of raw materials, organizational structure, processing conditions and other factors of fabric.
1 The influence of fiber composition
Different fibers and their fabrics, the degree of shrinkage are different, mainly depending on the hydrophilic properties of its fibers, that is, moisture-absorbing properties. The fabric with large moisture absorption, the fiber will produce expansion after immersion, the diameter increases, the length shortens, and the shrinkage condition is obvious. For example, viscose fiber absorption rate is large, like this kind of moisture-absorbent fabric, after washing will produce serious shrinkage. Synthetic fabrics, such as polyester and polypropylene, they are less hygroscopic, so the dimensional stability to washing is also smaller.
In addition, wool and other fiber fabrics with scale structure felt shrinkage, under the mechanical action of water, wool scale one-way irreversible phase jamming so that the wool fabric sustained felt shrinkage.
2 The influence of the fabric structure
The fabric itself has a different organizational structure and weaving tension, the shrinkage rate is different. Weaving tension is small, the fabric is tight and thick, the shrinkage rate of the fabric is small; weaving tension is large, the fabric is loose and thin, 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, the shrinkage rate is also close. The warp density of the textile is large, the warp shrinkage is large, and conversely, the weft density is greater than the warp density of the woven fabric, the weft shrinkage is also large.
In general, the dimensional stability of woven fabrics is better than knitted fabrics; the dimensional stability of high-density fabrics is better than low-density ones. In woven fabrics, the general shrinkage rate of plain fabrics is less than facecloth fabrics; and in knitted fabrics, the shrinkage rate of flat knitted organizations and less than ribbed fabrics.
3 The influence of the production process
Generally speaking, the fabric will be stretched by the machine during the weaving and dyeing process, and the processing time is long, so there is tension on the fabric. However, it is easy to release the tension after the fabric meets water, so we will find the fabric shrinkage after washing.
In addition, the textile fiber under the heat conditions, the form and size of the fiber changes and shrinkage, after cooling also can not return to the initial state, which is called heat shrinkage of fibers. For example, in the boiling water state, the shrinkage rate of processed polyester staple fiber is 1%, the shrinkage rate of vinylon is 5%, and the shrinkage rate of chlorine spandex in hot air is 50%. Heat shrinkage, mainly in polyester nylon this kind of thermoplastic chemical fiber above, improve the method is to do a good job in dyeing and finishing heat setting, through high temperature setting to make it obtain good dimensional stability.
From the influence of fabric shrinkage factors can be seen, fabric shrinkage is inevitable, so we need to carry out some necessary research on the shrinkage of fabrics.
1 Cotton and linen woven fabrics without stretch, the weft shrinkage control process in the control of the mercerization door width, rather than heat setting. Cotton and linen fibers are not as thermoplastic as polyester and nylon fibers (or in other words, the glass transition temperature of cotton and linen fibers is too high, the current sizing machine can not reach, even if it can reach the first coking rather than softening, so it is meaningless), so heat sizing does not make it like chemical fiber fabrics to obtain dimensional stability, only through the internal stress relief of mercerization, in order to obtain good dimensional stability.
2 In practice, for some non-elastic fabric, first pull to the extreme in weft, and then again over water retraction, may also partially improve its weft shrinkage, guess the reason is this: in the case of weft pull to the extreme, there is partial untwisting of the weft yarn, resulting in the improvement of the weft shrinkage. At this level, this method is only effective for light fabrics because the tension provided by the sizer is not sufficient to untwist the weftward yarns of heavy fabrics. It would be more effective for coarse and stiff yarn counts with low twist, because such yarns are more prone to untwist.
This method is only partially improved, shrinkage improvement data is also usually only 1% to 3%, and there is an adaptation to the fabric, is a last resort to save the emergency method. The normal practice should be to improve the mercerizing process.
3 The warp shrinkage of cotton polyester or cotton chinlon blending is usually not as large as 100% cotton fabrics, it only has the shrinkage caused by the “dry setting” deformation, but not the shrinkage caused by the increase of its winding process due to the weft fiber swelling.
4 Elastic fabric containing spandex must be heat-set to obtain good shrinkage, here are two methods: one is higher temperature and shorter setting time, and the other is lower temperature and longer setting time, they are equivalent in terms of obtaining good shrinkage of the fabric, but the former is more economical and the latter has better rebound effect latter.
Fabric Shrinkage Rate|Dimensional Stability to Washing: Test Method
Fabric shrinkage directly affects the stability of the garment shape and the beauty of the garment, thus affecting the use and wearing effect of the garment. So the fabric shrinkage rate that is the dimensional stability to washing is an important indicator to detect the quality of clothing.
1 Testing standards and instruments of fabric shrinkage
Common washing standards:
- International standards: ISO 6330, ISO 5077
- European Standard: EN ISO 6330, BS EN ISO 6330, DIN EN ISO 6330
- American Standard: AATCC 135
- Japanese Standard: JIS L 1930, JIS L 1906
- China Standard: GB/T 8629, GB/T 8930
2 Test procedures: washing, drying, and ironing
In the test procedure, JIS L 1930 and GB/T 8629 are basically equivalent to ISO 6330, and the washing procedure of the reference standard ISO 6330 is as follows.
There is another commonly used shrinkage test method in Japan is JIS L 1096, this method has different methods and parameter settings from A-G, which is a unique method in Japan.
If you compare the AATCC 135 (see below) and ISO 6330 washing program of type B, you will find that they have a lot of similarities. The ISO 6330 washing program of type B is like a combination of temperature, washing time and speed in AATCC 135.
For the choice of washing temperature in the test, American Standard and European Standard are based on the washing marking temperature, and Japanese Standard JIS L 1930 is also based on the washing marking temperature. The Japanese standard JIS L 1096 customer will specify the specific method, for example, the F2 method is 60℃, while the F3 method is 100℃. The Chinese standard is specified by the customer or refer to the corresponding garment standard, such as shirt standard, single clip garment standard, which will directly affect the specified washing procedure and temperature.
Q: What does the code “4N” mean in the test table?
A: The number “4” represents the temperature, 4 is 40℃; “N” represents the washing action, for example, “N” is normal agitation, “M” is gentle agitation, “G” is gentle agitation, “H” is imitation hand washing.
The greater impact on the shrinkage test data is its drying method, generally speaking, there are six drying methods: line dry, drip line dry, flat dry, drip flat dry, flat press, tumble dry.
But due to the different habits of the people in different countries, the drying method specified by the guests in the test is very different, for example, Americans generally do not dry clothes in the air but directly tumble, the American standard on the general use of rotary drying, this kind of shrinkage data obtained will be greater than other drying methods. And the Chinese people are basically drying in the air, so the national standard is also basically using the line dry method.
Common fabric washing and drying methods
|Composition||Washing / drying method (laboratory test method)|
|Cotton||40℃, tumble dry, line dry|
|Linen||40℃, tumble dry, line dry|
|Polyester||40℃, tumble dry, line dry|
|Viscose Fiber||30℃, flat dry|
|Wool||40℃, flat dry|
|Silk||40℃, flat dry|
Finally, choosing a suitable ironing temperature according to the composition of the fabric can also improve the shrinkage of the fabric, especially the fabric that wrinkles after washing. But ironing is not necessarily improve the results of the rate of change of fabric size, for example, cotton and linen fabrics can be ironed at high temperatures to improve the size of the shrinkage rate. But for synthetic fibers, high-temperature ironing does not necessarily improve its shrinkage rate, but will have damage to its performance, such as fabric hard and brittle, and even nylon fabric in the ironing data worse.
How to prevent clothes from shrinking during the washing and care process?
In the process of washing and caring for clothes, the water temperature, drying method and whether to add detergent will have an impact on the shrinkage of clothes. Washing care includes washing, drying and ironing, each of these three steps will affect the shrinkage of the fabric, so how to effectively avoid shrinkage of clothes?
1 Try to hand wash
Now many families have a washing machine, usually dirty clothes to the washing machine, in fact, the washing machine washed clothes not only did not clean thoroughly, but the clothes killing force is also very large, but also easy to lead to poor quality and shrinkage of clothes.
2 Read the washing instructions before washing
Do not do the same cleaning treatment of all clothes, according to the washing instructions for the appropriate care, like some clothes contain different ingredients, it is not suitable for washing machine, blind washing will only destroy the taking nature of the clothes.
3 Clothes should not soak too long
Many people are used to washing clothes before soaking for a period of time, soak clothes can, but the time has to be correct, the normal 10-15 minutes is enough, clothes soak for a long time after the dirt will be fiber anti-absorption, and some fiber texture will also become soft, destroy the taking of clothes.
4 Do not wash at high temperature
Washing clothes with high-temperature water is not disinfecting clothes, but in the destruction of the taking of clothes, the general temperature control of washing clothes at 30℃ or less can be.
By laying the shrunken clothes flat and setting them with an iron, the clothes will not only return to their previous appearance, but the problem of shrinkage will be relatively reduced afterwards.
6 Softener maintenance
In addition to washing clothes with soap and laundry detergent, you can also use some softeners and other maintenance under the clothes to prevent shrinkage.
7 Correct drying
When drying clothes, try to flatten and straighten, to prevent serious shrinkage, and do not wring the water too dry, so that the role of gravity, the clothes will not be so easy to shrink.