How much bamboo viscose shrinks and when it happens
Short answer: Viscose shrinks because its fibres are stretched during manufacturing and contract again with heat and moisture. It happens most in the first few washes, and most of all in the tumble dryer.
Why viscose shrinks
When viscose fibres are spun and knitted into fabric, they are pulled and stretched. That tension stays in the fibres. When the fabric gets wet and warm, the fibres relax and draw back towards their original length. That is why a new garment can come out slightly smaller after its first wash.
Heat is the trigger
Warm water and hot air make the fibres draw back. Without heat, it hardly happens. The higher the temperature, the more shrinkage, both in the washing machine and in the dryer. Stick to the temperature on the care label, or a little below it. See washing and care.
The first wash matters most
Most of the shrinkage happens in the first couple of washes. After that the fabric is usually stable, as long as you keep the temperature down. So the first washes are the ones to be most careful with. Wash cool and hang the garment to dry the first few times to see how it behaves.
The dryer is the worst
Water at 40 degrees shrinks fabric a little. Hot air in a tumble dryer shrinks it considerably more, because the fibres move while they are heated. That combination of heat and movement is what pulls the fabric together. Choose low heat if you use a dryer, or hang clothes up. See bamboo underwear for men.
Length or width
Knitted fabric does not necessarily shrink equally in every direction. A garment often gets slightly shorter while the width holds up better. You notice it on sleeves, leg length and the length of a top. Measure a new garment before its first wash, and you can see whether it has changed.
Can it be reversed
Partly. A shrunken garment can be stretched gently while damp and then dried flat on a towel. Pull evenly across the whole fabric, not just at the edges, so it does not go out of shape. It rarely returns fully to its original size, but it can often be worn again.
Elastic and waistbands
Shrinking is not the only thing heat does. The elastic in waistbands and edges weakens at high temperatures, so underwear sits looser even though the fabric has become smaller. It can feel as if the fit has changed in two ways at once. A low temperature protects both.
Buy with this in mind
If you are between two sizes, choose the larger one if the garment will go in the dryer. If it will be hung to dry, you can usually stay with your normal size. Think about how you actually wash, not how you ought to. See bamboo underwear for women.
In short
Viscose shrinks because its fibres contract with heat and moisture. It happens most in the first few washes and most of all in the dryer. Wash cool, hang clothes up or use low heat, and go for the larger size if you are unsure and always tumble dry. That keeps the fit.
Frequently asked questions
Why does viscose shrink?
Because the fibres are stretched during manufacturing and contract with heat and moisture. Without heat it hardly happens, so temperature is the most important thing to control.
When does it shrink most?
In the first couple of washes and most of all in the tumble dryer, where heat and movement act together. After that the fabric is usually stable if you keep the temperature down.
Can a shrunken garment be fixed?
Partly. Stretch it gently and evenly while damp and dry it flat on a towel. It rarely returns completely to its original size, but it can often be worn again.
You can find the full range at Bamboo-Clothing.com.
