Originally Posted by
wolfchild
There is no such thing as 100% breathable and 100% waterproof at the same time, such fabric doesn't exist... Even the most expensive and most technical fabrics which are advertised as waterproof and breathable will loose their breathability when physical exertion reaches a certain point. and overwhelms fabrics breathability..and then you'll end up soaked with sweat inside a so-called waterproof/ breathable fabric.
As I stated above, there are precise scientific measurements in the link I provided about how to measure breathability and waterproofness. This isn't rocket science and every outdoor sporting garment I see in Europe lists these specifications.
As far as percent breathable (as in 100%) like you stated, I don't have an idea what that sentence means as it's not in the commonly used units. If I started reciting power at the crank in Joules people would be scratching their head if if it's technically correct.
Here is a better description (please click on this link unlike that other one that people don't seem to be clicking on.)
https://www.evo.com/guides/outerwear-waterproof-ratings-and-breathability
If you read that quick article, you soon see that 100% breathable doesn't mean anything as it's nonsensical and not comparable between fabrics. The data should have absolute units (as they do.)