Why synthetic fibres do not absorb
Short answer: Polyester and nylon are made of plastic, and plastic does not bind water. The fibre can only move water along its surface, not take it in, and that explains both the quick drying and why odour arrives sooner.
The material repels water
The molecules that make up polyester have nowhere for water to bind. Water beads together on the surface and runs on, instead of entering the fibre. That is a completely different behaviour from natural fibres, where the fibre itself takes in water and holds on to it.
That gives quick drying
Because water never gets into the fibre, it only has to evaporate from the surface. That is why a polyester garment dries in a fraction of the time of one that has soaked water in. It is the big advantage of synthetic fibres, and explains why they are so common in sportswear. See bamboo pajamas for men.
And it gives odour sooner
Sweat stays on the surface together with the bacteria, because the fibre does not take it in. That is one reason synthetic sportswear smells sooner than natural fibres. Moisture and bacteria sit close to the skin, and when the garment warms up you notice quickly. See bamboo undershirt for men and bamboo underpants for men.
Why synthetic feels different on the skin
When the fibre does not absorb sweat, moisture sits as a thin film between skin and fabric. Some find that clammy, especially at rest. It is not a sign that the garment is badly made, but a direct result of the fibre being unable to take in water.
Are synthetics better for sport
For intensive training yes, if you can live with them smelling sooner. The quick drying is a real advantage when you move a lot and want to be dry again fast. For calm days and the night that advantage counts for little, and softness and comfort matter more.
Why blends are used so often
Blends are used because they combine the comfort of viscose with the quick drying of polyester. You get something of both in one fabric. The compromise is that a blend neither dries quite as fast as pure polyester nor feels quite like pure natural fibre, so it is about finding the right ratio.
Can the smell be washed out fully
Most often yes, but it takes a higher temperature than synthetics tolerate. Bacteria cling to the fibre surface, and a cold or lukewarm wash does not always remove them. Follow the care label and wash the garment soon after use rather than leaving it damp in the basket.
How to choose by need
Think about what the garment is for before choosing the material. If you are running or training hard, quick drying matters most, and synthetic can be a good choice. If you are sleeping, relaxing or having an ordinary day, a soft natural fibre is often more comfortable against the skin.
Frequently asked questions
Are synthetic fibres better for sport
For intensive training yes, if you can live with them smelling sooner. For calm days and the night, softness and comfort count for more than quick drying.
Why are blends used so often
Because they combine the comfort of viscose with the quick drying of polyester. The compromise is that a blend neither dries quite as fast as pure polyester nor feels like pure natural fibre.
Can the smell be washed out fully
Most often yes, but it takes a higher temperature than synthetics tolerate. Wash the garment soon after use and follow the care label, so the smell does not set so firmly in the fibre.
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