Blog Heat and sun
Polyester vs cotton in an Australian summer
Walk into most school uniform shops in Australia and check the labels. You'll find a lot of polyester: 100% polyester sports polos, 65/35 poly-cotton shirts, polyester-viscose trousers, polyester-blend dresses. It's durable, cheap, holds its colour and dries fast. There are good reasons it's so popular.
But is it the best fabric for a child sitting in a classroom on a 35-degree day? Let's compare honestly.
How they handle sweat
The biggest difference is how each fibre deals with moisture.
- Cotton is hydrophilic. It typically holds around 7 to 8.5% moisture at normal humidity without feeling wet, and it can absorb sweat and release it to the air.
- Polyester is hydrophobic. Its moisture regain is well under 1%. Sweat isn't absorbed by the fibre itself; it either moves through gaps in the fabric or stays on the skin.
In regular woven or knitted uniform fabrics, that difference is noticeable. Textile research comparing knitted fabrics found 100% cotton gave better air permeability and water vapour permeability, while 100% polyester held more heat.
The fair caveats
It would be misleading to say cotton always wins. Here's where polyester has the edge:
- Engineered sportswear. Specialised polyester knits with wicking yarns can move sweat away from skin very effectively during intense exercise. Some studies have found these fabrics feel cooler than cotton during hard workouts.
- Drying time. Polyester dries much faster after washing, and after a soaking.
- Durability and cost. Polyester resists wear and pilling, and it's cheaper to produce.
Cotton's weakness is that when it's completely saturated, it holds that water and can feel heavy and cool. That matters for a marathon runner. It matters much less for a child at a desk, at recess and in a 40-minute PE lesson.
What a typical school day needs
Most of a school day is low to moderate activity in warm conditions: sitting, walking, short bursts of play. In those conditions, a fabric that absorbs light sweat, lets air move, and feels soft against skin is usually the most comfortable choice. That's cotton's sweet spot.
Standard uniform polyester also isn't the engineered, wicking polyester found in elite sportswear. It's usually a plain, budget fabric chosen for durability, and it can feel clammy once a child starts to sweat.
Parents notice this too. It's common to hear that children feel hot and sticky in synthetic uniforms, and some schools have found their polyester PE tops are hotter to wear than cotton shirts.
Skin and synthetic fibres
There's also the skin itself. Polyester is commonly coloured with disperse dyes, some of which are recognised skin sensitisers. Children with eczema are often advised by dermatologists to wear soft cotton next to skin and avoid scratchy or non-breathable fabrics.
The verdict
| Cotton | Standard polyester | |
|---|---|---|
| Absorbs sweat | Yes | Very little |
| Air and vapour flow | Generally better | Generally lower |
| Dries quickly | Slower | Faster |
| Feel on sensitive skin | Soft, gentle | Can feel clammy |
| Durability | Good, especially tightly woven | Excellent |
For everyday wear in an Australian climate, especially for children with sensitive skin, natural cotton is the more comfortable choice for most of the school day.
That's why we're building the Natural Schoolwear range around natural fibres like cotton, chosen for long, warm days and gentle on skin from the first bell to the last.