How do you make a material breathable?

Functional clothing: which material is best?

Functional clothing: The materials in it decide - (Photo: © Maridav -

"When athletes start to freeze or sweat during training, the true quality of a textile becomes apparent," explains Silke Off, who heads the Clothing Physiology Laboratory at the Hohenstein Institute in Bönnigheim. We recommend the test seal “wearing comfort”, for which 5 criteria must be met.

The five important functions of functional clothing

  1. Thermal insulation: A small air cushion can form between the textile and the skin and also in the textile construction itself, so that body heat does not evaporate - ideally when dry and when wet.
  2. Sweat absorption: Well-constructed functional shirts made of wool, polyester and polypropylene can absorb a certain amount of sweat.
  3. Sweat transport: The absorption of liquid sweat, the transport from the inside to the outside of the textile and there the evaporation must work well.
  4. Breathability: The functional shirt lets water vapor through from the inside to the outside.
  5. Skin sensory: When sweating, the textile does not stick to the skin and does not raise any fibers that would scratch. The material doesn't feel too stiff or too limp.

"A damp functional shirt should be so dry after 20 minutes that it can insulate the heat again," explains Silke Off. It is easy to find out whether the material is suitable for endurance sports: place the material on the inside of your forearm or on the back of your hand for a while and watch whether the skin becomes damp quickly and the material sticks - if that happens, you sweat while running and cycling preprogrammed.

Materials for sportswear

A whole range of different fabrics are now available to manufacturers of sportswear. They each have different advantages and disadvantages, which we list here.

Merino wool

Nowadays, some functional shirts are made from the finest merino wool - mostly with a hydrophilic finish. The smooth threads have no scales that can stand up and scratch when you sweat.

Merino wool
+ feels comfortable on the skin
+ warms a little better than polyester
+ transports sweat
+ does not hold on to the smell of sweat so strongly that triathletes do not have to change their shirt until the third day.
- after repeated wearing it becomes matted into small nodules that can be plucked off or "torn off" with a special comb.
- Should be washed at 30 to 40 degrees in the wool program, the functional shirt shrinks at hotter temperatures.


The synthetic fibers can be smooth, swirled or curled. Textured yarns create air pockets on the skin, which can hold body heat. Smooth filament yarns feel cool and stick to sweaty skin.

About Karin Hertzer

Karin Hertzer from Munich is probably the only health journalist in Germany who knows everything about freezing and sweating. For her online portal she interviewed Ortovox and Icebreaker founder Jeremy Moon.

+ warms when it has been processed into a textured yarn
+ usually keeps its shape so that the functional shirts are durable for a long time
+ is suitable for heavily sweating athletes because it transfers sweat but does not absorb it
+ is very consistent
- does not rot and should therefore be properly recycled


The abrasion-resistant and lightweight synthetic fiber is used for functional shirts in various material thicknesses.

+ retains body heat just as well as wool
+ is breathable and more elastic than merino wool, polyester and cotton
+ absorbs almost no sweat, therefore hardly ever gets wet and dries very quickly
+ is very consistent
+ is suitable for triathletes who sweat a lot
- lets the water vapor condense on the inside of the functional shirt in athletes who sweat less, which can lead to freezing faster
- does not rot and should therefore be properly recycled


Pure cotton is only suitable as an outer layer for sports if the fabric has polyester on the inside. Some manufacturers offer cotton as an admixture.

+ feels comfortable on the skin when dry
+ cools and looks "cool" when wet
- does not warm
- stays wet for a long time, which can be very uncomfortable during breaks and in the wind

Mixed fabrics

Merino wool with polyamide or nylon: The synthetic fibers make the wool shirts firmer. Polyamide is sometimes also used on the inside of two-surface functional shirts. Polyamide forms chain molecules: With nylon, different types of single molecules are the basis for the fabric, with Perlon they are the same - but that makes little difference in terms of comfort.

Merino wool and cotton with elastane or spandex: The fiber is elastic, does not absorb sweat and breaks with long exposure to UV radiation. American manufacturers refer to elastane as spandex. Textiles of the legally protected Lycra® brand from Invista work in a similar way.

Additions with polyacrylics: The synthetic yarn absorbs the smell of sweat and holds it in place.

Cotton with polyester: The admixture allows the cotton to better transport the water vapor.

Cotton with polyester: As a result of the admixture, the cotton can better transport the water vapor.

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