Modern gore Tex (and similar) shell jackets often are marketed as being 2 or sometimes 3 layer construction with the Gore Tex membrane being one of the layers. Often the outer layer isn’t actually waterproof and can soak through. If gore Tex is the main functional layer why does there have to be extra material layers facing the elements?
In: Engineering
GoreTex wears off and needs replacing after a while. Having a layer on top protects it, allowing it to last longer. It also means that if it gets a tear, it’s less likely to damage the waterproof layer.
Same reason why you can’t use a fork on a nonstick pan.
Goretex is actually teflon, the same stuff they use on nonstick pans. Teflon isn’t that strong of a material so they layer it to protect it.
Also fun fact: the goretex patent expired decades ago, a lot of other stuff is made of PFTE (Teflon) these days and goretex isn’t particularly special anymore.
Second fun fact: PFTE is pretty bad for the environment, goretex themselves are trying to move away from it and some of their newer products labeled goretex don’t actually contain it.
Because the waterproof membrane is roughly the same as Teflon tape, and has all the resilience of tissue paper, but is also the main expense in the jacket.
The old paclite was about as minimal as they could go, and they discontinued it because it just wasn’t durable
Think of it like a sandwich with the jam being the Gore-Tex membrane.
Top layer:
The protective shell which defends the membrane from abrasions. It’s usually coated in DWR (durable water repellant) which is the chemical used to make water bead off the jacket.
Middle layer:
The gore-tex membrane which is fully waterproof yet breathable.
Bottom layer:
The layer of fabric that touches your body. It’s usually a softer material for comfort and protects the membrane from sweat and grime from your skin.
Often people think their jacket is no longer waterproof because water has stopped beading off of it. This is just because the DWR has worn off or is dirty. Wash your Gore-Tex. Dryer settings on high heat will rejuvenate it.
Source: I worked for Arc’teryx
what others have commented is mostly correct. but to add to it: Gore-Tex (and those like it) is a waterproof and (almost more importantly) BREATHABLE membrane. This means any moisture inside the jacket, like perspiration, can escape. Layering other fabric around the membrane protects it (outer layer) and/or makes it more comfortable against the skin (inner layer). the outer layer of fabric will have what’s called a DWR finish (Durable Water Repellant). It’s a hydrophobic coating (usually an oil or waxed based) that caused water to bead up and run off. This is NOT what makes the fabric ultimately waterproof—the membrane does that. Yes, it makes water bead up on the fabric and shed off, but if you were to submerge it in water without it being bonded to a waterproof membrane, it would leak. The DWRs primary purpose is to keep the outer layer of fabric from becoming saturated with water. if the outer layer of fabric gets too waterlogged, not only will your jacket now be heavier, it will suck all the heat right out of you making you feel cold. Furthermore, when the outer fabric layer gets saturated, the Gore-Tex (or other membrane) can no longer allow moisture (such as perspiration) to escape. This is a really important feature for the purpose of temperature regulation. If water is not beading up on your Gore-Tex jacket and you are wet inside the jacket, it is not the Gore-Tex failing… it’s your own sweat that cannot escape because the DWR has worn off the outer fabric.
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