Gore Tex is a brand which belongs to the Gore company. It has been around for decades, the first Gore membrane was developed in the 1960s. Gore Tex today is by far the standard membrane for giving waterproof apparel some breathability. In theory, a Gore Tex membrane allows steam to escape since steam drops are smaller than water drops. Gore Tex therefore keeps the rain or water out while allowing steam to escape.
Gore Tex works only when there is a temperature difference between the inside (should be at least body temperature) and the outside (should be cooler). In tropical climates it is useless. Gore itself does all kinds of things based on it’s initial invention, a polymer called expanded polytetrafluoroethylene (or ePTFE).
Unfortunately also one of the downsides of Gore Tex starts with this chemical. John Oliver, an English/American comedian has a great piece about it. Gore Tex is not exactly a fabric you want to have in your compost to produce new soil. The search for alternatives showed results: Dimpora is ready to produce much smarter membrane stuff.
From a long distance hiking perspective, Gore Tex and membranes in general have an additional problem. The membrane gets clogged. Sweat contains salt crystals and body oils. To have a working membrane you need to wash it after just 10 days of use. Says at least Christine Thürmer and she has possibly the right amount of experience to give an informed opinion on this subject. When hiking thousands of miles on the AT, this means that you need special care for your waterproof clothes often. If you have bad luck this means you would have to wash your GTX garments every other week, if you want it to work as intended.
If you want to maximize the effectiveness of washing your stuff, you need special detergent because the DWR (durable water repellent) on the outer fabric of your jacket also needs to be restored. Otherwise the outer fabric just soaks up water. In general the makers of such detergents say that it will work best, when the clothing is already clean. Therefore you need to wash it twice. It is common practice to wear rain gear while your other clothes get washed. Sometimes there are loaner clothes which you can wear or you are facing not having any clothes for two hours. Unless you have two sets of rain gear and the ability to rotate between the two (because friends or your butler wash it for you), Gore Tex isn’t exactly that useful for long distance hiking.
At the same time, there are no mass market alternatives. You can always ask somebody to do a custom trench coat for you but I didn’t find somebody willing to do it. Such a trench coat would be made out of robust fabric with no breathability at all. To assure a good ventilation, it would have long zippers under the shoulders. It would not have a hood because it would be combined with a waterproof hat. Why a trench coat? Because you could just make the jacket a little bit longer, reaching down to above the knees and you would have your shorts also protected from rain but at the same time you would benefit from the air around your legs.
Some UL hiking gear companies do their own jackets but unfortunately they do not have the best tailors in the universe. For the money you would spend on a specialist jacket you can get an Arc’teryx one. They come in all shapes, with Gore Tex just don’t count on the breathability because after 10 days it is gone.
I decided to go with the Patagonia Storm jacket, which is made out of recycled Nylon and no Gore Tex. I still try to modify it with zippers under the shoulders.