The myth that the tumble dryer only shrinks cotton
Short answer: The tumble dryer can shrink far more than cotton. Viscose, wool and garments with elastane are also affected by heat and movement in the drum. Viscose from bamboo is particularly sensitive, because its fibres swell in water and contract with heat.
Why clothes shrink
When clothes get wet, the fibres swell and the yarn relaxes. During production the fabric is often stretched, and the heat and tumbling of a dryer can let the fibres pull back into a more relaxed state. That is the process we experience as shrinking. It happens to varying degrees in every fabric made from fibres that absorb water. Cotton is the familiar example, but it is far from the only one that behaves this way.
Viscose and bamboo
Viscose, including viscose from bamboo, absorbs a lot of water and is weaker when wet. That makes it prone to shrinking, especially in heat. Many bamboo items should therefore not be tumble dried at all, or only on low heat. The same applies to textiles around the house, such as home and homewear in bamboo. Read the care label, and let viscose dry on a rack or flat on a towel instead of in the machine.
Wool felts in the heat
Wool has tiny scales on the surface of the fibre. Heat, moisture and movement make those scales lock into each other, so the fabric felts and draws together. That cannot be undone. This is why wool labels often say it must not be tumble dried. Some wool items are treated so they can be machine washed, but the tumble dryer remains a risk unless the label clearly states otherwise, so it is better to be cautious.
Elastane is damaged by heat
Elastane is found in sportswear, underwear, socks and many bras. The fibre provides stretch, but it is weakened by high heat. Over time the garment loses its ability to spring back and may feel slack or wavy. A bamboo sports bra keeps its support better if it hangs up to dry rather than going into the tumble dryer, where the heat steadily wears out the elastane inside the fabric.
Low heat is a compromise
Many tumble dryers have a gentle programme with low heat. That reduces the risk but does not remove it entirely. If you want to use the dryer, choose the lowest temperature, take the clothes out while they are still slightly damp, and let them finish drying on a hanger. Do not overload the drum, since that causes more friction and more creases. Always check the tumble drying symbol on the care label first before you start.
Good habits that preserve the size
Wash at a low temperature with a short spin. Shake garments out before hanging them and ease them gently into shape while damp. Hang knitwear and viscose flat or over a rail so the weight does not pull the fabric out of shape. Whether you buy clothes in the sale for women or anywhere else, the care is the same: read the label and do not guess when it comes to drying.
Frequently asked questions
Can shrunken clothes be stretched back
Knitwear and viscose can sometimes be stretched a little while damp. Felted wool cannot be restored.
What does the square with a circle on the label mean
It is the tumble drying symbol. Dots show the temperature, and a cross means the garment must not be tumble dried.
Do clothes only shrink the first time
Mostly the first time, but repeated heat can cause further shrinking over time.
You can find the full range at Bamboo-Clothing.com.
