Why the Membrane Isn’t Breathing

We've been using high-performance breathable fabrics for over 30 years. Sometimes they work great. Sometimes it’s just great marketing.

We've been using membrane fabrics for over 30 years. They work. Sometimes they don't. The difference has nothing to do with price - and everything to do with physics. This isn't an attack on manufacturers. Membranes make sense. But they work on their own terms - not yours.

For us, the key is versatility - gear that works in all conditions, no matter what we’re doing.

Do Membranes Really Breathe?

The first modern membrane was created in 1969 – a microporous, expanded Teflon structure we now know as Gore-Tex. Each square centimeter contains about 9 billion pores. These are small enough to block liquid water, but large enough to let water vapor pass through.

In short: -Water stays out. -Vapor can escape. But only if conditions allow it.

Cold or warm, wet or dry - layered clothing often makes more difference than any membrane ever could.

The Funnel and the Needle – A Simple Explanation

Imagine a huge funnel – one meter wide – ending in a needle as thin as one used for premature infants. Absurd? Yes. But useful as a metaphor. You’re wearing a sealed rubber suit and start to move. You sweat. Now pierce the suit with that needle. Water vapor starts to escape. Now pour water into the wide end of the funnel. It blocks everything. Nothing passes through the needle. That’s what happens when your jacket is soaked – the pores get clogged and stop breathing.

When the fabric is soaked, vapor can’t escape - the membrane stops breathing, no matter how advanced it is.

What is DWR?

DWR stands for Durable Water Repellent – a coating applied to outer fabrics. It helps water bead up and roll off instead of soaking in. DWR doesn’t directly affect the membrane, but without it, the membrane can't do its job. Once the fabric absorbs water, pores get blocked. DWR wears out. It’s broken down by: - dirt, sweat, oils, - washing with regular detergents, - overheating during drying, - skipping post-wash reactivation. How to care for it: - use proper cleaning agents, - avoid fabric softeners, - reactivate with low heat (tumble dry), - reapply waterproofing treatments regularly.

The DWR coating keeps the outer layer dry - without it, even the best membrane can’t do its job.

How to Check Your DWR in the Field

You don't need a lab. Pour a few drops of water onto the outer fabric of your jacket.

If the water beads up and slides across the surface – DWR is working. If it soaks in and the fabric darkens – DWR is gone.

That's it. This test takes 10 seconds and tells you more than any label.

A second signal that's easy to miss: so-called "wetting out." The jacket looks wet on the outside, but technically hasn't leaked – the membrane is still blocking water. The problem is that a saturated outer layer kills breathability just as effectively as a hole in the membrane. You feel wet, because you are wet – from the inside, from your own sweat.

That's why DWR isn't optional. It's a prerequisite for the whole system to work.

The same test applies to any DWR-treated fabric – a tent, shoes, a backpack. The principle is identical.

Active clothing works even when it's not raining – strong wind alone is enough to make a membrane jacket worthwhile. It's worth matching the type of membrane fabric to the conditions you're actually going out in.

In Practice

Step out into the rain. -If your jacket is dry – the membrane works. -With heavy rain and fresh DWR, it still works, but less efficiently. -Once the fabric is soaked, breathability drops to almost zero. You’ll stay dry from the outside, but wet from the inside.

Climbing in the zone of eternal snow means facing extreme contrasts - cold, heat, wind. The right clothing makes it possible to keep moving safely through it all.

What About Footwear?

Shoes are an even tougher case. If: - it’s dry, - the shoes are made of fabric (not leather), - no heavy insulation, - and you wear the right socks, then... the membrane might work at 10–25% of its theoretical performance. If: - the shoe is leather, - soaked by wet grass, - worn for long hours, then... it doesn’t breathe. Or works so poorly it’s irrelevant.

Well-chosen clothing means knowing when to swap layers - like trading a membrane jacket for a light windblocker that vents moisture far better than even the best Gore-Tex.

Clothing (Jackets, Pants)

Condition	Works Well	Reduced Function	Does Not Work
Dry jacket, functional DWR	yes
Temperature/humidity gradient	yes
Slightly damp jacket		reduced function
Minimal difference in temp/humidity		reduced function
Soaked jacket (DWR failed)			does not work
High ambient humidity			does not work

Avalanche rescue training isn’t real action - but when it’s -15°C, windy, and you’re sweating, clothing becomes one of the most critical parts of your gear.

Footwear

Condition	Works Well	Reduced Function	Does Not Work
Dry fabric shoes	yes
Low humidity, proper socks	yes
Thick leather or insulated boots		reduced function
Wet conditions, grass			does not work
Shoes soaked through			does not work

Monika during a tough ascent with full gear for a 10-day winter bivouac - staying warm comes not just from layers and membranes, but from boots, movement, and technique.

Shelters (Tents, Tarps, etc.)

Condition	Works Well	Reduced Function	Does Not Work
Dry climate, good ventilation	yes
Internal condensation (breathing)		reduced function
High humidity, no airflow			does not work
Soaked outer layer			does not work

Breathable Dry Suits :) ?

Some manufacturers now offer dry suits made with membranes - marketed as breathable. But the term deserves a closer look.

Some drysuits are called “breathable” - but underwater, no membrane breathes. Pressure and saturation block everything.

When Membrane Dry Suits Can Release Vapor

1. The suit is dry and not under water pressure (e.g., on surface breaks). 2. Clear difference in internal vs. external temperature. 3. Used in humid but non-submerged activities (kayaking, SAR).

Underwater, membranes can’t breathe - pressure and water block vapor from escaping, trapping moisture inside the suit.

When It Won’t Work

1. While diving – water pressure blocks diffusion. 2. The outer fabric becomes saturated. 3. Inner layers trap vapor before it reaches the membrane. 4. Extremely humid environment – no vapor pressure gradient.

Comfort in a drysuit comes from many things - proper fit, thermal layers, good valves, and skill. A “breathable” membrane? That’s either not on the list… or somewhere near the very end.

A membrane drysuit makes sense in specific situations: a long day on the water in cold conditions, SAR operations, surface intervals between under-ice dives. In these cases a membrane can genuinely move vapor – and that's a legitimate advantage.

The problem starts when a manufacturer sells "breathability" as a feature of a diving drysuit without that context. Underwater, no membrane breathes. Hydrostatic pressure at even a few metres of depth is enough to block vapor diffusion through any porous material. This isn't a question of membrane quality – it's physics, and no laminate changes that.

Thermal comfort while diving depends on suit fit, insulation layers and valves – not the membrane. If you see "breathable drysuit" in a product description intended for diving, treat it as information about surface use, not underwater performance.

You don't need to know everything about membranes. But understanding the basics will help you make better choices – and save you some money.

How to Spot Truly Breathable Membranes

Just because a label says “breathable” doesn’t mean it is. Look for: - RET values (below 6 = excellent breathability), - Independent testing (e.g., Öko-Test, EMPA, Stiftung Warentest),- Intended use: alpine, ultralight, ski-touring gear uses better membranes (e.g., Gore-Tex Pro, eVent DVAlpine),- Construction: 3-layer laminates with minimal insulation breathe better. Manufacturers like Arcteryx, Montane, Tilak, Patagonia, Brynje, Fjällräven (Eco-Shell), or Hestra (gloves) tend to use materials that really breathe – but even they won’t work in all situations.

RET value	Breathability	Typical use
Below 6	Excellent	Alpine, ski touring, high-output activities
6–13	Good	Hiking, trekking, general outdoor
13–20	Moderate	Light rain protection, low activity
20–30	Low	Casual waterproofs, umbrellas
Above 30	Not breathable	Rain capes, basic waterproofs

RET (Resistance to Evaporative Transfer) measures how much a fabric resists the passage of water vapor. The lower the number, the less resistance – and the more freely moisture escapes.

Softshell often outperforms a membrane jacket on the way up – its open, stretchy structure lets moisture escape more freely. Most softshell fabrics also carry a DWR coating, so the same rules apply: once it's gone, the fabric wets out and performance drops.

Conclusion

A membrane is a tool. It works when conditions allow – and doesn't when they don't. Price, brand, and pore count don't change that.

A thousand-dollar jacket follows the same physics as a cheap one. Once the outer layer saturates, breathability drops to zero. That's not a product flaw. That's how physics works.

Know the limits. Maintain the DWR. Match the membrane to the conditions.

Sometimes you test your gear in alpine snowstorms, sometimes during a rainy mushroom hunt - either way, a wet jacket still won’t breathe.

With the right layering, the whole world is within reach - “bad weather” is just weather that calls for the right clothing.