warming boots

I cannot comment on what might have been used during WWII, but most of the hand-warmers nowadays are made with a (non-metallic) mineral known as Vermiculite. You can search some web-sites for hand-warmers and they may even describe the method of operation.

Thank you, will look at it.

Now you can get the battery powered version.

Another alternative is thermal socks. I've just ordered some for standing around in cold muddy fields in my spare time.

Try this thread.

Thank you, I was actually looking at what there may be a substance/material that will give out heat but not as a result of a chemical reaction but from pressing, rubbing, stirring in case of liquid, etc that is, mechanical force applied to it.

Hi guest - though I note my original post was voted off topic and now interestingly has been removed - the answer remains the Japanese feet were the energy source.

However; your rephrasing is noted;

So: what you seek is a material with flexing heat production.

Jule did the work on that and its not much - given feet are providing the HP.

So; what you want is that small heat directed in one direction - foot-ward.

Thinking through this; "conductive" on one side and "insulating" on the other.

This in turn suggests; a laminate of materials.

That then suggests a laminate with a high frictional coefficient at the interface.

I came across this;

Think about the journalist take on what is happening - and then what is actually happening.

http://www.trendhunter.com/trends/fat-burning-underwear-nanofiber-scuffs-off-your-skin