What is Gore-Tex?

It's a sheet of stretched plastic with nine billion pores per square inch, glued between the fabrics you can actually see. Knowing what that membrane does — and what the layer sitting on top of it does — explains nearly every complaint people have about expensive rain gear.

ExplainersPublished August 3, 202611 min read

Gore-Tex is a brand, not a fabric. What you actually buy is a laminate: a very thin membrane, about a hundredth of a millimetre thick, bonded between the outer fabric you can see and whatever sits against your arm. The membrane is the waterproof part. Everything else is there to protect it or to make it wearable.

That membrane is expanded PTFE — Teflon, stretched until it tears open into a microscopic mesh. Gore's own figure is nine billion pores per square inch, each one around 20,000 times smaller than a raindrop and 700 times bigger than a molecule of water vapour. Liquid water can't get through. Vapour can. That gap has been the entire idea since 1969.

It's also where the disappointment comes from. Almost every "my Gore-Tex leaked" story turns out, on inspection, to be a story about the layer sitting on top of the membrane rather than the membrane itself. So it's worth taking the thing apart.

The stack

A rain shell, from the outside in

Four things are doing work in a waterproof-breathable jacket, and they fail in a very particular order. Reading them outside in makes the rest of this article mostly obvious.

The face fabric, and the DWR on it

The bit you can see, and the bit that goes first

What it is: Woven nylon or polyester, treated with a water-repellent finish
Its job: Make water bead up and roll off before the weave soaks
How long it lasts: Gore is blunt about it: DWR isn't permanent

The outer fabric isn't waterproof and was never meant to be. It's there to take the abrasion — pack straps, granite, branches — and to hold a chemical finish called DWR, for durable water repellent. DWR is what makes new gear do the thing everyone films: water standing up in beads and rolling off.

Gore lists what kills it, and none of it is exotic. Dirt, detergent residue, sunscreen, body oils and ordinary wear. It is a surface treatment on a fabric you rub against things all day, so it goes first, usually long before anything else on the jacket is worn out.

Why it matters: This is not the waterproof layer, and it is the layer that fails. Nearly everything people blame on Gore-Tex is happening right here.

The membrane

The waterproof one

What it is: Expanded PTFE, or expanded polyethylene in newer fabrics
Thickness: About 0.01 mm, by Gore's figure
Its job: Stop liquid water, pass water vapour, block wind

On its own this stuff is delicate — it's roughly 70% air by structure, which is exactly why the pores are there. It can't be a garment by itself, so Gore bonds it to an outer textile and a lining, and that sandwich is the laminate.

The membrane doesn't wear out the way the DWR does. What ages is the rest: Gore notes that the glues and adhesives holding the construction together degrade eventually. A shell that's genuinely letting water through is usually one with a hole in it, a failed seam, or years of hard use behind it.

The backer

Where 2-layer, 2.5-layer and 3-layer actually differ

2-layer: Membrane bonded to the outer fabric, with a loose drop liner hanging inside
2.5-layer: A printed or sprayed coating instead of a liner. Lightest, clammiest
3-layer: Outer fabric, membrane and a bonded inner textile, all one piece

The numbers on a hangtag are counting how the inside of the jacket is finished, and the reason any of it exists is that bare membrane doesn't cope with being handled. Early Gore-Tex had a real problem with body oils contaminating the laminate, and a backer is the answer to that.

Three-layer is tougher and generally packs down less small; 2.5-layer is the lightest and the one most likely to feel sticky against a bare arm; 2-layer sits in between and turns up on jackets built for wearing around town as much as up a hill. None of them changes how waterproof the membrane is.

The seam tape

The layer nobody thinks about until it matters

The problem: Every stitched seam is a row of needle holes through the laminate
The fix: Waterproof tape heat-bonded over the seam from the inside
On a spec sheet: "Fully seam sealed" and "critically taped" are not the same claim

You can build a perfect membrane and then punch a few thousand holes in it with a sewing machine. That is not a hypothetical: the first generation of Gore-Tex rainwear in the late 1970s leaked at the seams badly enough that jackets came back in bulk, and seam tape is the fix Gore developed in response.

It's still the detail worth checking on a cheap shell. Fully taped means every seam; critically taped means the shoulders and hood got tape and the rest took its chances.

Wetting out, and why a good shell stops breathing

When the DWR stops working, rain no longer beads on the face fabric — it spreads out and soaks into the weave. That's wetting out, and it's the single most useful piece of vocabulary in this whole subject.

A saturated face fabric puts a film of liquid water directly against the outside of the membrane, and vapour cannot cross that. Treeline Review put it about as plainly as it can be put: once a jacket's face fabric wets out, it doesn't matter how good the rest of the layers are, because the jacket has stopped being able to breathe. Your sweat now has nowhere to go, it condenses on the inside, and you arrive at the car convinced the jacket failed.

There's a second limit underneath that one, and no amount of maintenance fixes it. A membrane moves vapour down a gradient — from the warm, humid air next to your skin toward drier air outside. In heavy rain the outside air is close to saturated and the gradient narrows, so the fabric breathes less well exactly when you most want it to. Add a steep climb, which produces sweat faster than any membrane on the market can shift it, and the honest answer is that you will be somewhat wet.

The choice is whether that's your own sweat or forty degrees of rainwater.

Which is why I'd rather set the expectation properly: a shell keeps the weather off and keeps the wind from stripping your heat. It is not a dehumidifier.

A rain shell shoulder and sleeve gone dark and patchy with water, the surface soaked flat instead of beading — Wetting out: the water has stopped standing up in beads and soaked into the face fabric instead. The membrane underneath is still waterproof — but with a film of water against it, almost nothing is getting out.

Bringing a tired shell back

This is Gore's own care routine for outerwear, and it costs nothing to try before you buy anything. Check your garment's own care tag first — Gore says to, and a few of their fabrics have their own rules.

01
Wash it, properly
Machine wash at 105°F / 40°C with a small amount of liquid detergent, rinse twice, and keep the spin low. Skip powder detergent, fabric softener, stain remover and bleach — residue left in the fabric is part of what stops water beading in the first place.
Washing a shell more often than feels natural is the counterintuitive part. Dirt is the enemy of DWR, not the wash cycle.
02
Dry it, then keep drying it
Tumble dry on a warm gentle cycle or line dry. Once it's dry, Gore's instruction is to tumble it for a further 20 minutes — the heat reactivates the DWR that's still on the fabric. A surprising number of jackets start beading again at this point and need nothing else.
03
Only reproof if it still won't bead
If water is still soaking in after a wash and a tumble, the finish is genuinely spent. Reapply with a wash-in or pump-spray DWR product. This is the step people jump to first, and it's the one most often not needed.
04
Activate the new finish
After treating, tumble dry for 20 minutes, or iron gently with a cloth between the iron and the garment and no steam. Fresh DWR mostly needs heat to set.
Gore-Tex Shakedry garments are the exception to all of this: gentle wash at 40°C, no tumble drying, no ironing, no DWR treatment.

From a snapped rod to a PFAS-free membrane

Useful context, because two of the things people argue about — seam tape and forever chemicals — make much more sense with the dates attached.

1969
Bob Gore yanks a heated rod of PTFE
He had been trying to stretch PTFE slowly and watching it snap. Out of frustration he pulled one fast, and instead of breaking it expanded — into a microporous structure that is mostly air. Expanded PTFE, ePTFE, later patented and branded Gore-Tex.
1976
The first product isn't a jacket
It's a two-person tent from Early Winters, a Seattle outfitter. Rainwear and sleeping bags followed within a year, and the material went from laboratory curiosity to something you could buy.
Late 1970s
It leaks, and gets fixed
Rain came through the seams and body oils contaminated the fragile laminate. Early Winters' founder described jackets coming back like crazy. Gore's answer was seam tape, a revised membrane and roughly $4 million of first-generation fabric taken back. The outerwear business turned its first profit in 1979.
2017
The chemistry commitment
Gore pledges to remove what it calls PFCs of Environmental Concern from its consumer laminates — the general weatherproofing fabrics by the end of 2020, the specialised ones by the end of 2023. That target was the water-repellent treatments, not the membrane.
2022
A membrane that isn't fluorinated at all
Announced in late 2021 and in shops from autumn 2022, the ePE membrane swaps expanded PTFE for expanded polyethylene, in a laminate Gore describes as PFC-free including its DWR.
2025
The hard-use fabrics follow
Gore-Tex Pro, the construction used for mountaineering and ski shells, moves to the ePE membrane too. If you buy a shell now, which membrane is in it depends on the model.

When waterproof-breathable earns its place

The membrane is expensive and it is not always the thing your day needs. Two lists, and most people's honest answer is a bit of both.

Worth the money

Sustained cold rain, where staying dry stops being about comfort. The Park Service's line at Point Reyes is that getting wet from rain or fog cools you fast once there's a breeze on you, and hypothermia there is a year-round risk.
Wind. The membrane is windproof, and wind is what actually strips heat off you.
Shoulder season and winter, when air temperatures are low enough that you aren't sweating hard anyway — which is precisely when a membrane breathes best.
Wet brush and snow against your legs, where a soft shell just soaks.
Short outings in bad weather, where you're not working hard enough to out-sweat the fabric.

Think twice

Hot, humid days with a climb in them. The gradient the membrane needs isn't there, and you'll be wet from the inside whatever you spent.
Waterproof footwear in hot, dry country. It runs warmer, and anything that comes in over the cuff has no way back out.
Long-distance walking where your feet are going to get wet regardless. Drying fast beats staying dry for the first ten minutes, which is why so many thru-hikers walk in non-waterproof shoes.
A summer afternoon shower. Breathability is doing almost no work in that hour, and something simple and unlined is fine.
Any shell whose DWR you have no intention of ever maintaining. Untended, the expensive one ends up performing like the cheap one.

If you remember four things

The membrane is the waterproof layer, and it's not the one that fails. The water-repellent finish on the outer fabric is, and it fails within seasons rather than years.
Feeling damp inside usually means the face fabric has wetted out, not that the jacket is leaking. Gore says as much in their own FAQ.
A wash and 20 minutes in a warm tumble dryer fixes more jackets than a bottle of reproofer does. Try that order.
Gore-Tex is one brand of waterproof-breathable laminate, not the category. Plenty of in-house membranes do the same job, and the same physics limits all of them.

Trail running shoes vs hiking boots

Photo: Grand Canyon National Park — Public domain

Safety

Hiking in the heat

Where this shows up in gear

The waterproof-or-not decision bites hardest on footwear, because you can't take a boot's membrane off when the weather turns.

Best Hiking Boots of 2026

Read the guide →

The words on the hangtag

ePTFE: Expanded polytetrafluoroethylene. PTFE — Teflon — stretched until it opens into a microporous film. The original Gore-Tex membrane, and still in plenty of current fabrics.
ePE: Expanded polyethylene. Gore's newer membrane, in products from autumn 2022. Not fluorinated, which is the point of it.
DWR: Durable water repellent. A finish on the outer fabric that makes water bead and roll off. Not waterproofing, not permanent, and the first thing on a shell to stop working.
Face fabric: The outer textile — the surface you see and touch. It carries the DWR and takes the abrasion, and it is not the waterproof layer.
Wetting out: When the face fabric soaks through instead of shedding water. The membrane stays waterproof; breathability collapses, and the jacket feels clammy.
Laminate (2L / 2.5L / 3L): How the membrane is sandwiched. 2-layer has a loose liner hanging inside, 2.5-layer a printed coating, 3-layer a bonded inner fabric. A durability and comfort choice, not a waterproofness one.
Seam tape: Waterproof tape bonded over the inside of stitched seams, because needle holes are holes. Fully taped covers every seam; critically taped covers the worst of them.
Hydrostatic head: How tall a column of water the fabric holds back before it pushes through, in millimetres. Around 10,000 mm is the usual floor for hiking and 20,000 mm for genuine all-weather use. Gore doesn't publish this figure for consumer garments — they sell against their own Guaranteed To Keep You Dry promise instead.
MVTR: Moisture vapour transfer rate — grams of vapour through a square meter of fabric in 24 hours. Published figures run from under 10,000 to about 40,000. Higher is more breathable, and lab conditions flatter every one of them.
RET: The other breathability measure, from a sweating hot-plate test run at skin temperature. Lower is better, which is the opposite of MVTR, which is why comparing two brands' numbers is so often useless.
PFAS / PFCs of Environmental Concern: Long-lived fluorinated chemicals. Gore's position is that PTFE is a fluoropolymer but not a PFC of environmental concern, and that its commitment targeted the repellent treatments. Not everyone accepts that distinction — broader definitions of PFAS do include PTFE — and the ePE membrane sidesteps the argument by not being fluorinated at all.

Questions people actually ask

Is Gore-Tex actually waterproof?

The membrane is, and it stays that way. Gore's pores are around 20,000 times smaller than a raindrop, and the membrane doesn't lose that with age. What degrades is the water-repellent finish on the outer fabric and, over a long enough life, the adhesives holding the construction together.

Why does my Gore-Tex jacket feel wet inside?

Almost always because the face fabric has wetted out. With liquid water lying against the outside of the membrane, your sweat vapour can't get through and condenses on the inside. Gore's own FAQ says a garment can feel damp and clammy without leaking. Wash it, tumble it warm for 20 minutes, and see if it beads again.

How long does a Gore-Tex jacket last?

Longer than the DWR on it, by a lot. Expect to be washing and reactivating the repellent finish within the first season or two of regular use, and to be doing that many times over the life of the garment. Gore's own answer is that the components — glues and adhesives especially — degrade eventually, and that care extends the useful life considerably.

Is Gore-Tex PFAS-free now?

Some of it. The ePE membrane is not fluorinated and reached shops in autumn 2022, and Gore-Tex Pro moved to it for autumn 2025. Plenty of ePTFE product is still sold, and PTFE is a fluoropolymer. Gore committed in 2017 to removing what it calls PFCs of Environmental Concern from its consumer laminates by the end of 2023, but that commitment was aimed at the repellent treatments, not the membrane. If it matters to you, check which membrane the specific garment uses.

Do I need Gore-Tex boots?

Less often than the shops suggest. A membrane in footwear helps in cold, wet, shoulder-season conditions and on short walks where dry feet are the point. It runs warmer in hot country, and once water comes in over the cuff it has no way out. For long distances where your feet will get soaked anyway, most experienced walkers pick shoes that drain and dry fast instead.

Is Gore-Tex better than the membranes brands make in-house?

Sometimes, and not automatically. Gore-Tex is one brand of waterproof-breathable laminate with a long track record and a guarantee attached to the black hangtag. The physics is the same for every membrane, in-house ones included: none of them will breathe well through a soaked outer fabric, and none of them will keep up with you on a hard climb in the rain.

Can I wash a shell in a normal washing machine?

Yes, and you should. Gore's instruction for outerwear is 105°F / 40°C with a small amount of liquid detergent, two rinses and a low spin. What you avoid is powder detergent, fabric softener, stain remover and bleach — the residues they leave are part of why water stops beading.

Sources

Facts on this page were checked against these. Conditions, fees and rules change — check the official page before you go.

The GORE-TEX Membrane: What it is, how it works and why you need it — GORE-TEX Brand (W. L. Gore & Associates) · checked August 3, 2026
Frequently Asked Questions — GORE-TEX Brand (W. L. Gore & Associates) · checked August 3, 2026
Care Instructions: Outerwear — GORE-TEX Brand (W. L. Gore & Associates) · checked August 3, 2026
Responsible Usage of Fluorochemicals — GORE-TEX Brand (W. L. Gore & Associates) · checked August 3, 2026
Introducing our new expanded Polyethylene (ePE) membrane — GORE-TEX Brand (W. L. Gore & Associates) · checked August 3, 2026
GORE-TEX Pro garments — GORE-TEX Brand (W. L. Gore & Associates) · checked August 3, 2026
Robert W. Gore — National Inventors Hall of Fame Inductee — National Inventors Hall of Fame · checked August 3, 2026
Bob Gore's Cozy Revolution — Science History Institute · checked August 3, 2026
How Breathable Is My Waterproof? — Rab · checked August 3, 2026
How Waterproof Jackets Work: Membranes, Ratings and Breathability — Alpkit · checked August 3, 2026
10 Best Lightweight Rain Jackets of 2026 — Treeline Review · checked August 3, 2026
7 Best Waterproof Hiking Boots of 2026 — Treeline Review · checked August 3, 2026
Your Safety: Hypothermia — Point Reyes National Seashore — National Park Service · checked August 3, 2026
PFAS Explained — US Environmental Protection Agency · checked August 3, 2026

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A rain shell, from the outside in

The face fabric, and the DWR on it

The membrane

The backer

The seam tape

Wetting out, and why a good shell stops breathing

Bringing a tired shell back

Wash it, properly

Dry it, then keep drying it

Only reproof if it still won't bead

Activate the new finish