Bamboo underwear for winter and where the layers belong
Short answer: The inner layer should move moisture, the middle layer should insulate and the outer layer should keep the wind out. Swap the order and none of them works properly, however much you have on.
The inner layer moves moisture
If the inner layer is damp, it cools the skin no matter how much is on top. Moisture draws heat from the body far faster than dry air. That is why the material of the inner layer matters most. It should sit close to the skin and pass moisture outwards. See bamboo undershirts for men.
The middle layer insulates
Insulation comes from still air, not from thick fabric as such. Two thin layers create a pocket of air between them, which one thick layer does not do in the same way. The middle layer can be a jumper or fleece that holds air without squashing the other layers. See bamboo underwear for men.
The outer layer keeps wind out
Wind strips away the air that insulates. Even a warm middle layer does little if the wind blows straight through it. A windproof outer layer holds the warm air in place, which is why a thin shell over a jumper is often warmer than a thick knit on its own.
The legs get forgotten
Most people layer the upper body and leave the legs with nothing. Yet the legs have a large surface, and thin trousers alone give little protection from cold and wind. A thin layer under your trousers often does more than another jumper on top, especially when standing still outdoors. See bamboo long johns.
Avoid sweating through
If you dress too warmly before you set off, you sweat and the inner layer turns damp. Start a little cool and take a layer off when you warm up. Open your jacket during hard activity so moisture can escape, and close it again when you stop to rest.
Fit of the inner layer
The inner layer should sit close but not tight. If it is loose, it cannot draw moisture from the skin, and cold air pockets form. If it is too tight, it restricts circulation and feels uncomfortable after a few hours. A soft, stretchy model follows the body and lies flat under the rest.
Washing that keeps it working
Fabric softener leaves a film on the fibres that stops moisture moving through the inner layer. That puts the whole system out of action, as moisture stays against the skin. Wash at 40 degrees with a mild detergent, skip the softener and air dry. See washing and care.
Adjust to the day
A cold, still day calls for more insulation in the middle, while a windy day calls for a better outer layer. If you will be very active, a good inner layer matters more than a thick middle one. Think in layers you can add and remove rather than one big garment.
In short
Moisture on the inside, air in the middle and windproof on the outside. Keep the inner layer dry, give the air room between layers and remember your legs. Wash the inner layer without softener so it keeps moving moisture. That way you stay warm without wearing more than you need.
Frequently asked questions
Why do I feel cold even with lots of clothes on?
Because the inner layer is damp. Moisture draws heat from the skin however many layers are on top, so start with an inner layer that moves moisture away.
Are two thin layers warmer than one thick one?
Yes, because the air between the layers insulates. Two thin layers create a pocket of air and are also easier to adjust as you warm up or cool down.
Why wear layers on the legs?
Because most people only layer the upper body, and the legs have a large surface. A thin layer under your trousers often does more than an extra jumper on top.
See our range of Boody underwear.
