There are various ways to prevent clothes from shrinking online, such as adding vinegar and putting borax, but there is no scientific and rigorous explanation. So today I will explain to you with a scientific and rigorous attitude: why clothes shrink and what to do if they shrink.
Clothes shrink because the yarn expands;
Don't doubt, yes, contraction is due to water absorption and expansion!
Generally speaking, the fabric is made up of warp yarns and weft yarns. After absorbing water, the yarn will expand in different degrees, which will lead to the increase of fiber diameter. Warp and weft are intertwined, and the intersection between them is fixed. If the diameter of the weft yarn increases, the length of the warp yarn must be increased to keep the weft yarn wrapped.
After natural drying, due to the friction between fiber yarns, the free movement of the yarns is limited, and the fabric still maintains its shrinkage shape. After the fabric is dried in water, the area often decreases, the thickness increases and the surface is uneven.
As can be seen from the above figure, after puffing, compared with before puffing, the yarn diameter becomes larger, the distance between yarns is closer, and the fiber curvature increases.
Part of the yarn length is consumed in the bending part, which will lead to smaller fiber shrinkage. After the clothes are dried, it is difficult to restore them to their original state under natural conditions because of friction.
Shrinkage is a state that most fibers exist, but the degree of shrinkage is different:
Generally speaking, the shrinkage rate of natural fibers (cotton, wool and silk) is higher than that of chemical fibers (polyester, nylon and acrylic). Because the structure and water absorption of natural fibers are different from those of chemical fibers. For example, cotton T-shirts that are often bought in summer often shrink (low-quality cotton fabrics are easier to shrink, while high-quality cotton fabrics are shrink-proof). However, the shrinkage phenomenon of nylon fabric jacket is difficult to observe.
Methods to prevent shrinkage:
The performance of high-quality fabrics is different from that of low-end fabrics. In order to prevent the fabric from shrinking, the finishing part of the dyeing and finishing factory will have shrink-proof treatment.
Setting method: mercerizing (cotton fiber is forced to expand and set under tension with concentrated sodium hydroxide solution)
Resin finishing method (bonding with fiber increases the barrier of chain diffusion and movement, and at the same time blocks the -OH hydroxyl group, which reduces the water absorption capacity. )
Pre-shrinking method: the fabric is forced to shrink by washing and mechanical force, thus reducing the shrinkage rate in the hands of consumers.
It is difficult for our consumers to carry out shrink-proof water treatment after buying clothes (iron ironing will have a certain shrink-proof function. )
What about shrunk clothes?
I regret to tell you that the shrinkage of fabric is irreversible, so it is difficult to change it back. (Because of the frictional resistance between fibers and the interweaving resistance between yarns. )
Let the clothes be washed with wet water again, and then fix the stretching with external force. This method is prone to uneven stress, resulting in different size specifications from those before washing. At the same time, it can't fundamentally solve the problem of clothes shrinking, and it will still shrink after washing again.
I have some suggestions for shrinking clothes:
1, if you want to fundamentally solve the shrinkage problem, please choose high-quality fabrics, low-end fabrics will save shrink-proof finishing because of cost saving.
2. Dry cleaning is recommended for clothes sensitive to shrinkage, and dry cleaning solvents are not easy to make fibers swell.
Don't try to add vinegar and soy sauce on the Internet easily, which will cause irreversible dyeing and damage to some fibers.