The fabric stretches over the course of the day
Short answer: Viscose fibres give a little as they warm up and pick up moisture from the body. Choose a quality with a bit of elastane, and let the garment rest a day so the shape returns on its own.
Why it happens
Bamboo viscose is a soft fibre that absorbs moisture from the air and the skin. As body heat warms the fabric and sweat dampens it, the fibres slide slightly against one another, and the garment grows longer and wider over the course of the day. It shows most at knees, elbows and the seat, where movement is greatest.
How much is normal
A couple of centimetres over the course of a day is common in thin fabric without elastane. More than that suggests a quality knit loosely at the factory, or a size that was too big from the start. A little elastane in the blend holds the shape far better through a full workday.
Getting the shape back
Lay the garment flat for a day, so the fibres settle back naturally without any help. A wash at thirty degrees and drying flat brings it fully back into shape. Avoid hanging heavy, wet garments on a hanger, since the weight pulls the fabric out right while it is at its softest.
Choosing right from the start
For clothes worn all day, pick a quality with elastane and a size that fits close without pulling anywhere. For nightwear and loungewear, stretch matters far less, since it does not need to hold its shape through a full day of movement and strain away from home.
Difference between loose and fitted cuts
A fitted garment stretches proportionally less than a loose one, since the fabric already sits close to the skin with less room to slide. A loose cut has more free fabric that can give, so stretch becomes noticeably more visible over an ordinary day of moving around.
How the season affects the stretch
In summer, when both humidity and body temperature run higher, viscose fibres often stretch more than in dry, cold winter weather. If a garment that normally fits well suddenly feels loose in the heat, moisture from the air is far more likely the cause than the fabric itself changing.
Testing a quality before buying
Run your hand lightly across the fabric and watch how quickly it springs back to its original shape. Fabric with a bit of elastane springs back instantly, while pure viscose stays stretched for a moment. This simple test gives a quick sense of how much a garment will likely stretch in use.
See also
If you already own a garment that stretches more than you like, it can still work well for lounging at home even once it no longer fits perfectly out and about. See bamboo leggings for women and women's bamboo pants for styles with a bit of elastane.
Loungewear is a different matter
For a quiet evening at home, a couple of extra centimetres at the waist mean nothing, and soft, stretchy fabric is actually an advantage here rather than a downside. See bamboo loungewear for women for pieces built exactly for that use, without needing to hold a tight shape all day.
Frequently asked questions
Does the stretch always come back
In fresh fabric, yes, almost always on its own after a day of rest. After many washes and a lot of daily wear, some of it eventually becomes permanent.
Does washing cold help
Yes. Heat and hard spinning pull hardest on the fibres and make the stretch permanent faster, while a cold, gentle wash holds the shape for longer.
Should I buy a size smaller
No, not as a solution to the problem. Choose a quality with elastane in your normal size instead, so the garment fits correctly from the very first day.
You can find the full range at Bamboo-Clothing.com.
