Why thirty degrees is sometimes not enough
Short answer: Fat from the skin only begins to loosen at around forty degrees. At thirty, part of it stays in the fibre, and that is what smells when the fabric warms up again. That is why clean washing can still smell after a day on the body.
Thirty degrees is a good habit
Thirty degrees is a sensible standard for most textiles. It is gentle on the fabric and the colours, and it copes well with ordinary dirt. But fat from the skin is not the same as dirt, and this is where thirty degrees can fall short, especially on close-fitting clothes worn all day.
Fat has a melting point
Skin fat is solid at room temperature and soft at body temperature. The wash water has to go above that point before the soap can loosen it effectively. If the water stays below it, some fat remains in the fibre as a thin film you can neither see nor feel, but which the odour later comes from.
Why the smell returns
The residues in the fibre only smell once the fabric warms up again. That is why a garment can smell neutral in the wardrobe and still smell after a few hours on the body. The heat wakes the fat and the bacteria left behind, and the process starts over even though it was washed.
Enzymes can compensate
A detergent with enzymes can break down fat and protein at a lower temperature, but it takes longer. Enzymes therefore help those who want to stay at thirty degrees. They do not fully replace heat, but they move the limit. See bamboo footies for men as an example of clothing that is washed often.
Why a long programme works
An hour and a half at forty degrees removes more than half an hour at sixty. Time and chemistry work together, and more time lets the detergent reach the fat. A long programme is often the best choice for clothes that sit close to the skin. See bamboo compression stockings and bamboo tennis socks for men.
Can I wash everything at forty degrees
Most basic items tolerate forty degrees, but the care label decides. Thin and elastic fabrics can lose their shape if washed too warm. If you are unsure, choose a slightly longer programme at the temperature on the label rather than guessing and risking the fit.
Polyester sportswear is different
Polyester sportswear rarely tolerates more than forty degrees, and it is clothing that often smells. Here a programme with more time helps more than a higher temperature. A detergent with enzymes and a wash without fabric softener is a good combination, because softener can leave a film that holds on to fat.
Small habits that make a difference
Wash clothes before the smell has time to settle, and take them out of the machine as soon as the programme ends. If they dry quickly and fully, the bacteria have less to live on. If you wash a lot at thirty degrees, take a longer programme now and then at the highest temperature the label allows.
Frequently asked questions
Can I wash everything at forty degrees
Most basic items tolerate it, but check the care label for thin and elastic fabrics. If you are unsure, stay with the temperature on the label and choose a longer programme instead.
What about polyester sportswear
It rarely tolerates more than forty degrees, so use a programme with more time instead. A detergent with enzymes helps too, and you can leave out fabric softener, which can hold on to fat.
Why does the smell return when it gets warm
Because the residues of fat and bacteria in the fibre are only released when the temperature rises. Washing warmer or with a longer programme gives the detergent a better chance of removing them fully.
You can find the full range at Bamboo-Clothing.com.
