Having received some bamboo walking socks for Christmas I thought I would test some of the claims for bamboo clothing seen online. Primarily, trying to understand whether it really is a warmer material than wool. There are some pretty wild claims out there, e.g. “three times warmer than wool” (but I won’t name and shame). Whilst sceptical of that specific claim, I do suffer pretty cold feet in the mountains in the winter, I am always keen to see if any kit will offer an advantage.
Out of the box, the bamboo socks I am using for the test are comfortable and well fitting. These specific Bam socks are actually a blend, with around 60% Bamboo and the rest Merino wool with a bit of polyamide.
I am putting them up against a couple of different wool socks, my typical winter hiking choice of Smartwool cushioned hiking socks with a 71/28/1 merino/nylon/elastene blend and an older pair of wool blend socks with a 70/30 wool/polyester mix.
The weigh in
The smartwool sock is a bigger heavier sock than the bamboo weighing in at 65g versus the 49g for the bamboo. However the second wool sock weighed in at just 35g so was a lighter option.
As well as tested the socks dry, I am keen to explore the performance of damp socks. So also tested insulation with the damp sock. Additionally as a bonus test I then wore the damp socks for a while to meaasure how warm the damp version kept my feet.
Test Method
I used the same test method as for the earlier wool versus synthetic blanket test and silk sleeping bag liner test. This is a simple method based around insulating identical cups with the material, filling with 200ml of hot water, at around 37-40 degrees, before measuring heat loss over time.
For the damp sock test, I soaked each sock in the sink, ensuring each was well squeezed underwater to become fully saturated. I then wrung the water as much as possible out of the socks before repeating the above test.
All tests were repeated three times to get an average result. Energy loss in kJ from the water was calculated using the standard approach (volume * specific heat capacity of water * temperature loss).
The results
So for the dry sock test it was a win for the wool. The smartwool sock retaining an average 18% more energy than the bamboo, the light wool sock retaining 16% more energy than the bamboo. This was somewhat of a suprise as the lighter wool sock performed nearly as well as the Smartwool sock.
How about warmth when wet?
Did the bamboo perform better than the wool when damp? The simple answer is no. Worse in fact. This time it allows the loss of 24% more energy than the bamboo.
The final test of wearing the damp sock and than measuring foot skin surface temperature validated this finding somewhat with the damp bamboo shod foot falling in temperature a full degree C colder than the wool shod foot.
Strikingly the bamboo also absorbed water extremely easily. When I was soaking the socks for the wet test it immediately sank and became saturated. The wool sock in comparison required wringing underwater to take on as much water. It’s hard to say how this will effect use. We want socks to draw moisture away from the skin so perhaps a further test on moisture transfer would be useful.
The verdict – Should I swap my wool hiking socks for bamboo?
The results were pretty clear. For absolute warmth the wool won this battle handily in both wet and dry. So if I am heading to the hills in cold or damp conditions it’s the wool socks that will go in the pack.
Now this doesn’t mean I don’t like the bamboo socks or that they don’t have their place. They are very soft and comfortable to wear with a good fit. I also believe that bamboo has some real potential from a sustainability perspective given how fast it grows and how robust it is. Notably the bamboo socks contained the smallest amount of added plastics versus the wool blends.
Smartwool socks, other brands exist of course, are available from a variety of places including Amazon:
The above link is an affiliate link. Whilst I have not association with the brand, nor have recieved any compensation for this article, if you click the above link and shop I may receive a small commission.
To see a video of the test click here: