Cotton Properties

Cotton absorbs moisture almost instantly, and thanks to the hollow centre of the fibre, the lumen, it releases that moisture just as quickly back into the surrounding air. A standard regain of 8.5% under the ISO test means the fabric doesn't turn unpleasantly damp or clingy even during heavy sweating. That's why cotton t-shirts and bedding stay comfortable even on hot days.

Pure cotton cellulose is one of the safest materials for direct skin contact and rarely triggers an allergic reaction. A score of 95 out of 100 makes it the material of choice for underwear, children's bedding and clothing for anyone with atopic dermatitis. Any irritation is usually caused not by the fibre itself but by additives such as dyes, formaldehyde in easy-iron finishes, or pesticide residues.

With proper care, a cotton fabric can withstand 200 to 300 wash cycles before visible signs of wear appear. This reflects the fibre's fairly high mechanical strength, though it still falls short of synthetic fibres when it comes to resisting stretching. In practice, a well-maintained cotton garment can serve for years of regular use.

A single cotton fibre reaches a strength of 28 to 40 cN/tex, and its strength actually increases by 18 to 25% when wet. This is one of the few properties where cotton gets stronger rather than weaker when soaked, which explains why it copes so well with frequent, intensive washing. It also means the fabric rarely tears during a normal machine wash.

Poor crease resistance is cotton's most well-known weakness, a result of cellulose chains that bend out of shape easily under pressure. A score of just 25 out of 100 means the fabric needs regular ironing if a smooth finish matters to you. A mercerised finish or an elastane blend can partly offset this.

Choosing the right washing temperature comes down mainly to colour. Coloured garments wash best at 30 to 40 degrees to protect the dyes from fading, while white cotton can safely go up to 60 degrees without damaging the fibre. Higher temperatures remove bacteria and soiling more effectively, but they also speed up natural wear.

Cotton tolerates fairly high ironing temperatures, from 150 to 200 degrees, setting it apart from more delicate synthetic fibres. The best results come from steam ironing while the fabric is still slightly damp. A temperature that's too low won't smooth the fibre properly, while the right setting can tame even a badly creased shirt.

The first wash accounts for most of a cotton fabric's shrinkage, since it releases tension built up during manufacturing. Depending on the temperature, shrinkage ranges from 2 to 4% at 30 degrees up to 5 to 8% at 60 degrees and above. The process is irreversible, so new clothes are best washed separately and at a lower temperature than the target, unless the label indicates a sanforized fabric.

As a purely plant-based cellulose fibre, cotton breaks down in soil within just 1 to 5 months, earning it the maximum biodegradability score. Polyester, by comparison, takes over two hundred years to do the same. That means worn-out cotton clothing or cloths can be composted or left to decompose naturally, rather than sitting in landfill for decades.