The most common mid layer for skiers is the polar fleece. It’s actually one of the most effective fibres that owes its success to its heat/weight ratio, its softness and its rapid drying capabilities. Loved for its cosy comfort, the fleece is also very breathable and strong, yet lightweight and easy to wash.
Fleece consists of synthetic fibres such as polyester, PET (polyethylene terephthalate) and others, sometimes recycled. It is available in different weights, allowing for different warmths. The type and intensity of physical activity to be performed guides the choice of weight, or grammage, of the fleece. For alpine skiers who ski on groomed trails, a high grammage is recommended (around 300g/m2), while for ski tourers who perform more intense exercise, a thin and breathable fleece layer is better.
Synthetic or natural, other insulating fibres can be used in mid layer manufacture. A broad choice of mid layers are available meet all needs and preferences — warmth level, fabric weight, fabric density and water repellency.
Polyamide, polyester, acrylic, polypropylene and others are chosen according to intended use of the finished product. The warmer a mid layer is, the less breathable it will be. However, these synthetic fibres ensure faster drying time than natural fibres.
Natural down can be found in micro-down jackets. Highly effective in terms of insulation and compression, down loses performance in damp conditions. Another natural fibre merits consideration: Merino wool. More expensive than synthetic fibres because it’s more effective, Merino fibre has other advantages. This incredible insulating fibre has the ability to regulate body temperature. It stays warm in cold weather and cool in hot weather. Shawn from a breed of New Zealand sheep, this wool is three times finer than traditional wool. Another advantage: it is a biodegradable fibre,, plus it’s easy to look after and is odour resistant.