The blend in a bamboo sock

Short answer: Bamboo viscose moves moisture faster than cotton and smells later. Wool keeps you warm even when it is damp, and synthetic fibres wear longest. Most socks are a blend, and that is usually a sensible solution.

Bamboo viscose

Bamboo viscose takes moisture from the skin and passes it on to the air. That keeps the foot dry, and it matters more for comfort than thickness does. It also smells later than cotton, because there is less moisture for anything to grow in. That is why many choose it for socks worn all day.

Cotton

Cotton absorbs well but releases the moisture slowly. The foot gets wet and stays that way. For a day spent sitting down that is fine, but for an active day it is less good. Cotton is soft and familiar, so it can suit quiet days. See bamboo socks for men as an alternative.

Wool

Wool holds the warmth even when it is damp, and it is therefore often used on cold days and in winter boots. On the other hand it is warmer than bamboo viscose, and that can be too much in closed shoes indoors. Choose wool if you know you will stand still in the cold for long.

Synthetic fibres

Synthetic fibres wear longest, and that is why they are often used where the sock is under most strain. They move moisture well, but feel less soft against the skin. A small share of them in a blend makes the sock more durable without changing the comfort too much.

Blends

Most socks are blends with a little elastane to hold the shape and a little polyamide in heel and toe for durability. That is a sensible combination. The fibres complement each other, and you get a sock that is both soft and keeps its form. See bamboo socks for women for examples.

How much elastane

Two to five percent elastane is enough to hold the sock up. More makes it tighter, but not necessarily better. The elastane usually sits in the cuff and helps the sock follow the foot, so it does not fold or creep down under the heel as you walk.

One hundred percent bamboo

One hundred percent bamboo sounds good, but it is not the best choice. Without elastane the sock loses its shape quickly, and without polyamide the heel and toe wear faster. That is why a blend with a high share of bamboo viscose is often the best solution if you want a sock that is soft and lasts.

Socks for sport

For sport a sock with a good fit matters more than the fibre alone. It has to sit close so it does not chafe, and it has to move moisture away from the foot. See bamboo tennis socks for men if you are looking for a sock for active days.

How to choose

Look at the composition label and see how large a share is bamboo viscose and what the rest is. Think about what you need the sock for. In closed shoes bamboo viscose is cooler than wool, and on winter walks in the cold wool can be better. There is no single right answer for everyone.