Originally Posted by genieskip
Breathable stuff will leak sooner or later. Rubberized stuff will get you wet with perspiration from the inside. Nothing's perfect - you choose your poison. The wettest I've ever been offshore has been with GoreTex FWG that was more like a sieve than any real protection - admittedly a long time ago but I've been skittish about the material ever since.
In order for Gore-Tex to allow water vapor to pass through the membrane it needs the outer fabric it's laminated to to not totally "wet out". If the jacket has lost it's DWR (durable water repellency) then it makes it significantly tougher for the Gore-Tex to breathe and pass vapor through.
The wet you experienced is most likely your own body vapor being trapped by significantly reduced breathability most likely due to "wet out" of the outer fabric.
The pores in the PTFE membrane Gore-tex is made of are physically too small for a water molecule to pass through. If you want to prove this theory simply place a Gore-Tex garment over a dry cereal bowl and depress the garment to make a catch basin. Then pour some water onto the jacket. It will not leak through.
I remember when gore-Tex first came out they had these store displays which were a tall cylinder with a Goretex membrane in the middle. The top of the cylinder was filled with water and the bottom was air with a small pump. You could pump air into the cylinder and watch the bubbles rise up through the water but the membrane never let water in.
Gore-tex is indeed water proof but you sweat and produce much more vapor than you realize and you get wet from the inside not the out.. Also when the fabric wets out and comes in contact with your skin it can actually cause condensation on top of sweat..
Hope that makes sense..
Oh and you can use NikWax TX Direct to re-apply the DWR to any Gore-tex garment if it's wetting out..