Underwear should be breathable and quick-drying, protect from overheating and cold, and thus enable the wearer while being active, a pleasant body climate. On the market, you can find products made of natural fibres and synthetic fibres, which have, in their own way, different benefits in supporting the functions mentioned above. To help facilitate the decision with the overwhelming spectrum of underwear and base layers that are offered in today’s market, we have compiled the most important features of merino and synthetic fibres.
Merino: Fine sheep
Merino wool is part of fine wool and comes from Merino sheep, most of which are located in Australia, New Zealand or South Africa. Clothing made of Merino wool is available in different versions: 100% Merino such as baselayers by Bergans, fabrics blended with elastane like Icebreaker underwear, or polyamide, as is the case in the expedition line from Devold, which combine the benefits of Merino wool with those of synthetic fibres.
Characteristics of Merino wool
Moisture absorption:
Wool absorbs water vapour and can hold about a third of its weight in moisture without feeling damp. Despite the retention of moisture inside the fibre, the fibre surface is water repellent, so that the material feels dry.
Heat insulation/breathability:
Thanks to the many air pockets inside the lying crimped fibres, the wool remains insulating even under wet and cold conditions. The air chambers also contribute to rapid moisture transport and temperature regulation so that merino wool is warm when it’s cold and cool when it’s warm!
Skin-friendliness:
Merino fibres have a much thinner diameter, so they do not scratch as opposed to conventional wool. Fine merino wool is very soft and contrary to the old belief that wool scratches, amazingly comfortable to wear.
Odour:
Merino wool is antibacterial. Bacteria find it difficult to lodge on to the wool fibre scales so that even after extremely long periods of wear there are no unpleasant odours.
Synthetic fabrics
Synthetic fibres can be basically divided into two types. There are fibres made from natural polymers, which are chemically processed. These are made from cellulose fibres such as viscose and modal, from which usually thin, silky fabrics are produced. They feel pleasant on the skin but aren’t so robust. The second group are pure synthetic fibres made from synthetic polymers such as polyamide and polyester. Synthetic base layers usually consist of these two fibres or blended fabrics, often in conjunction with elastane. Brands such as Patagonia or Houdini use recycled polyester and bluesign-certified production processes in order to make their products more environmentally friendly.
Qualities of synthetic textile
Moisture absorption:
Polyester and polyamide retain virtually no moisture, they can, however, carry moisture away from the body, via cavities in textured yarn (capillaries) so the garment stays dry even in times of high aerobic exertion.
Heat insulation / breathability:
Via a special spinning process, insulation can vary. Depending on your needs there is functional underwear or base layers in which the main focus is either on moisture transport or thermal insulation.
Skin-friendliness:
For people with particularly sensitive skin, fabrics made from synthetic are particularly suitable because only fine, soft polyamide and polyester fibres are used, which provide a very comfortable feel.
Odour:
Synthetic fibres have a smooth surface on which bacteria can keep better, which is why they smell faster. An additional chemical treatment can prevent odours.
Conclusion: merino or synthetic?
Our experiences have shown that merino underwear for more extensive planned tours is especially good as it remains odourless even after having been worn for longer periods. A change of clothes is not needed, thus saving space and weight in your luggage. What’s more, Merino wool provides a soft feel with its fine structure and excellent temperature regulation. Merino underwear is available in different strengths, so you do not have to miss the comfort of merino in the summertime.
Synthetic fibers in functional underwear are particularly quick-drying and have a high tear and abrasion resistance. The soft fibres are particularly kind to the skin and ensure a high wearing comfort. Via advanced technology they also feature odour-resistance and a cooling effect on the skin.