Can "restoration detergent" restore a shrunken sweater to its original state? Learn these tricks and wear your sweater for many more years

Author: Zhang Desuo: Associate Professor of the School of Textile and Clothing Engineering, Soochow University, and the National Engineering Laboratory for Modern Silk

Reviewer: Zhang Jie, Chief Engineer of China Textile Construction Planning Institute

gossip

Soft and sticky cashmere sweaters and warm sweaters are definitely the protagonists in the winter wardrobe. However, if you accidentally wash the wrong size, the tragedy of M becoming XS will happen. Moreover, the better the material, the smaller it will shrink. Clothes worth hundreds or thousands of dollars will become unwearable. Anyone would feel sad.

However, recently some "restoration tools" have begun to appear on the market - detergents specially used to wash shrunken sweaters and other wool and cashmere products. It is said that using "restoration detergents" to wash shrunken sweaters can restore them to their original state after washing. Is it really so magical?

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analyze

Reasons why wool clothing shrinks

Related to its structure

Many consumers think that cashmere is fine wool, but it is not. The wool we usually refer to is sheep wool, and cashmere is goat wool. In addition to coming from different sheep, they also have great differences in performance, price, etc.

For example, the fiber diameter of cashmere is thinner than that of fine wool, so cashmere products feel softer, smoother and more comfortable to wear; cashmere has better stretchability and elasticity than wool. In addition, cashmere has a low yield and is a rare special animal fiber.

A goat produces about 75 grams of hairless cashmere per year. In other words, the cashmere produced by five goats in a year can only be used to weave one ordinary cashmere sweater. Therefore, cashmere products are much more expensive than wool products.

The shrinkage phenomenon of wool fabrics is generally called " felling ", and the key reason for the shrinkage phenomenon lies in the structure of wool itself.

Schematic diagram of the structure of wool fibers at different levels (Source: Textile Materials Science, Editor-in-Chief: Yu Weidong)

The fiber structure of wool and cashmere contains a scale layer, the main function of which is to protect wool or cashmere from changes in properties caused by external conditions. It is also this scale layer that, under the action of moisture, heat and chemical reagents, and repeatedly squeezed by mechanical external forces, causes the fiber to produce irreversible directional movement, causing the fiber aggregate to gradually shrink and tighten, and interweave and entangle with each other, forming a felted fabric.

Think back to when we wash wool and cashmere products, whether by hand or machine, we are actually providing conditions for shrinkage. Therefore, it is not surprising that wool products shrink, which is its inherent characteristic. On the contrary, wool products that do not shrink or shrink very little generally have a low wool content.

But it does not mean that the better the quality of wool products, the more they will shrink. There are differences in the surface scale structure of sheep wool and cashmere. The scale spacing of sheep wool is small and the scale density is also large, ranging from 16.2 to 34.9/mm; while the scale spacing of cashmere is large and the scale density is smaller than that of wool, ranging from 10.3 to 15.6/mm. Based on the above data, we can know that wool shrinks more than cashmere. Therefore, cashmere products with a better feel actually have a much smaller chance and magnitude of shrinkage than wool products.

SEM image of sheep wool

Cashmere Scanning Electron Microscope

(Li Weihong, Xi Bin, Guo Tianfen, et al. Identification of sheep wool and cashmere[J]. Hubei Agricultural Sciences, 2011, (3): 544-545.)

Shrinkage recovery agent

Is it really possible to restore your beloved clothes to their original state?

There are some wool and cashmere product shrinkage recovery cleaning agents on the market, and there are also some related shrinkage recovery methods on the Internet. So can these recovery cleaning agents and recovery methods really restore shrunken wool products as you wish?

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We have learned that the fundamental reason for the shrinkage of wool products is the irreversible directional friction of the scales on the wool surface. Therefore, the key to preventing the shrinkage of wool products is to reduce the friction of the scales. Therefore, in the textile industry, wool and cashmere products are usually subjected to shrinkage-proof finishing by chlorination, oxidation, bio-enzyme, coating, etc. The essence of this method is to remove the scale layer on the fiber surface or smooth the edge of the scale layer by chemical or biological methods, or wrap the scale layer by coating to achieve the effect of reducing directional friction.

If you want to restore the shrunk wool products, you need to untangle the wool fibers. Generally speaking, use hot water or steam to swell the wool, reduce the entanglement between scales, and make the fibers and scales soft. Then use external force to stretch the scales to untangle them and restore them. During the stretching process, you can use an iron to keep the clothes moist and at a high temperature, keep the scales soft, and achieve a better stretching and recovery effect.

Similarly, shrinkage recovery cleaning agents are essentially some surfactants and softeners. Their purpose is to make the fibers softer and reduce the friction coefficient of the fibers. When using these so-called recovery agents, they also need to be stretched to restore them.

Therefore, if there is no restoring detergent, the softener commonly used at home can achieve a similar effect, and even the conditioner we use daily can play this role. There is also a type of shrinkage restorer, which is a chemical reagent that has a slightly soluble effect on wool scales. It achieves the purpose of relieving shrinkage by dissolving entangled scales, but it causes great damage to wool products and is not recommended.

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Master the correct washing and care methods

Minimize the chance of damage

When washing wool and cashmere products, you must first choose the right detergent. There are special detergents for wool and cashmere products on the market. In addition, you also need to pay attention to the following when washing:

① Wash separately, use appropriate water temperature (below 30℃), avoid using hot water, and the water should cover the fabric.

② Use an appropriate amount of detergent and wash for a short time: For a normal-length, fitted wool sweater, just pour 20ml of detergent. For men's sweaters, pour more. Stir and disperse evenly with your hands, press the fabric a few times, turn it over and press it a few times again. Do not rub it repeatedly. Rub the key parts, such as the collar and cuffs.

③ When rinsing, hold the fabric with both hands and squeeze out the water. After rinsing, do not wring it. Wrap the fabric with a clean towel and squeeze out the water.

If you want to keep the original texture of the fabric after it dries, there is another trick: after rinsing, pour a basin of clean water directly into the basin, just enough to soak the sweater, then pour in softener (about 1 bottle cap), or pour in 1 bottle cap of glycerin and stir well, and finally put the fabric in to fully soak for 10 minutes. After taking it out , squeeze out the water, lay it flat in the clothes drying basket and dry it in a cool place.

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Note: Do not pick up wool products with one hand. A sweater soaked with water is very heavy and will deform! Do not twist the fabric with your hands or hang it on a regular hanger to dry, as this will deform the fabric. Always use a drying basket. Do not expose the fabric to the sun. Fabrics of different colors should not be washed together to avoid staining.

in conclusion

"Recovery detergent" is actually not magical, and ordinary softener has similar effects.

Shrinkage recovery is not suitable for severe shrinkage. It is difficult to grasp the correct force when ironing and pulling the fabric at the same time. It is easy to over-pull the fabric and deform it. It is better to pay more attention to the care of wool products, especially when washing clothes.