Why wool sweaters shrink and how to avoid it
Wool sweaters are warm and comfortable, but they also have a drawback: they tend to shrink if they are not washed and dried carefully. But why does this happen? And how can it be prevented or remedied?
To answer these questions, the article on the Knitalongclub.com website comes to our aid.
How to shrink a wool sweater?
The shrinkage of woolsweaters is due to two main factors: the structure of the wool fibers and the washing and drying conditions.
Wool fibers are composed of an internal part called the cortex and an external part called the cuticle. The cuticle is made up of overlapping scales that open and close depending on temperature and humidity. When wool fibers are wet and subjected to heat or friction, the scales open and hook together, forming knots that make the fabric more compact and smaller. This process is called felting.
Washing and drying conditions influence the degree of felting of wool fibers. In particular, the factors that favor the shrinkage of wool sweaters are:
- Hot water, which opens the cuticle scales and makes them more adherent to each other.
- The aggressive detergent, which alters the pH of the wool and makes it more sensitive to heat and friction.
- The mechanical movement, which causes the fibers to rub and knots to form.
- Hot drying, which fixes the shrinkage and makes it difficult to recover the original shape.
How to prevent wool sweaters from shrinking?
To prevent wool sweaters from shrinking or felting, you need to follow some precautions when washing and drying them. Here are some tips:
- Wash wool sweaters by hand or in the washing machine on a delicate program and at a low temperature (maximum 30°C).
- Use a specific detergent for wool or a neutral soap, which does not damage the fibers and maintains the natural pH of the wool.
- Do not rub, twist or wring wool sweaters, but pat them gently with a towel to remove excess water.
- Dry wool sweaters flat on a dry surface away from direct heat or sunlight, which can discolor or dry out the fibers.
- Do not use a dryer, iron or steam, which can cause irreversible shrinkage of wool sweaters.
How to fix shrinkage in wool sweaters?
If your woolen sweaters have already shrunk, there are some methods that can help you recover their original shape or at least reduce the damage. Here are some examples:
- The soaking method: immerse the wool sweater in a solution of warm water and hair conditioner or white vinegar for about 15 minutes, then rinse and dry flat, gently pulling the sweater in tight areas to widen it.
- The ice method: place the wool sweater in a plastic bag and then in the freezer for at least 12 hours, then let it thaw at room temperature and dry flat, gently ironing the sweater in the tight areas to widen it.
- The ironing method: humidify the wool sweater with a spray bottle and then iron it with a low temperature iron and with a cotton cloth on top, gently pulling the sweater in the narrow areas to widen it.
These methods do not guarantee total recovery of the original shape of wool sweaters, but they can help improve the appearance and fit. However, prevention is always the best way to preserve your wool sweaters and enjoy their warmth and softness.
