How moisture travels between two layers
Short answer: Moisture moves from the wet to the dry and from the warm to the cold. Two layers of clothing that touch therefore exchange water all the time. The chain is only as strong as the outermost layer, which has to release the moisture into the air.
Moisture seeks the dry
Moisture always travels from a place with a lot of water to a place with little, and from warm to cold. The body is warm and damp, and the air outside is often cold and dry. So moisture moves outward through the clothing, layer by layer, as long as there is a difference to even out between the layers.
Contact is a precondition
If the layers lie close, the water can be pulled onward by capillary action, the same force that lets a cloth soak up water. If there is air between them, the moisture must first evaporate and then condense again in the next layer. That is slower and can leave moisture in the innermost layer.
The outer layer sets the pace
If the outer layer cannot pass moisture on to the air, the whole chain stops. Water then builds up in the innermost layer, however good it is. That is why buying the most expensive base layer is no use if the jacket over it is completely tight. The chain is only as strong as its weakest link.
Why layering only works in order
Innermost a layer that moves moisture, then insulation, and outermost something that lets vapour escape. Swap the order and the moisture collects inside. This applies on a hike, but also in daily life, where a thick layer inside and a tight one outside give a damp feeling. Think about the order when you get dressed.
Underwear as the innermost layer
The innermost layer receives the moisture first. If it lies close enough for the moisture to be pulled onward, and loose enough for air between layers two and three, the chain works. For daily wear you can look at bamboo underpants for men and bamboo undershirt for men as an example of an innermost layer.
Snug or loose
The layers should fit snugly enough for contact, but loosely enough for air between layers two and three. If everything is tight, the clothing becomes one block where moisture cannot move freely. If everything is loose, the innermost layer loses contact with the skin. A sensible compromise is an innermost layer that fits close but does not squeeze.
Does the same apply in bed
Yes. Sheet, duvet and nightwear exchange moisture in exactly the same way. If you sleep in a thin layer under a thick duvet, moisture collects in the nightwear when the duvet is tight. Browse our bamboo sleepwear for men, and air the duvet in the morning so the moisture can escape.
Why the innermost layer gets wettest
The moisture comes from the body and can only move on if the rest allows it. If a tight layer sits outside, the innermost layer is where the moisture ends up. It is not a sign that the innermost layer is bad, but that the chain of outer layers is slowing things. Open or remove a layer and the moisture can move on.
The main thing to remember
Moisture travels from the wet to the dry and from warm to cold, and all layers take part. The outermost layer sets the pace, so make sure it lets vapour escape. Also keep the order right, with layers close enough for contact and loose enough for air. That is how you stay dry.
Frequently asked questions
Should the layers fit snugly or loosely
Snugly enough for contact, loosely enough for air between layers two and three. If everything is tight, the clothing becomes a block and moisture cannot move freely.
Why does the innermost layer get wettest
Because the moisture comes from there and can only move on if the rest allows it. If a tight layer sits outside, moisture builds up in the innermost layer.
Does the same principle work in bed
Yes. Sheet, duvet and nightwear exchange moisture in exactly the same way. If the duvet is tight, moisture collects in the nightwear, so airing the duvet in the morning helps.
You can find the full range at Bamboo-Clothing.com.
