Why Does a Membrane Stop Breathing?
By TaVare · updated 2026-08-03
When a membrane stops breathing and it turns clammy and sweaty inside the jacket, the cause is usually that its pores are clogged from the inside – by body oils, sweat, deodorant and dirt – not that the membrane is broken. The fix is therefore a proper wash, not fresh proofing. Here is why it happens, how to open breathability up again, and when the jacket should go to a professional.
How a membrane actually breathes
A breathable membrane lets water vapour out while stopping liquid water from getting in. Sweat that evaporates off your body is a gas, and it passes through the membrane's micropores or hydrophilic film and out into the air. But breathing depends on the pores being open and on a moisture difference between the inside and the outside. If something forms a film – on either the inside or the outside – the vapour stalls, condenses inside the jacket, and you experience it as clammy and 'sweaty'. The jacket is not leaking; it simply cannot vent the moisture you are producing yourself.
Two different causes – don't mix them up
'A clammy jacket' has more than one explanation, and they call for different treatment. Work out which one you have before doing anything:
- Inside clogging: body oils, sweat, deodorant, sunscreen and dirt settle in the pores from the inside. This is fixed by washing, not proofing.
- Outside wetting out: when the outer fabric soaks up water because the DWR is worn, the wet layer forms a barrier that stops vapour escaping. It also feels clammy, but is solved with fresh proofing.
- Delamination: the membrane peels away from the fabric and forms bubbles or flakes. This is damage, not dirt, and cannot be washed or proofed away.
How to open breathability with the right wash
If the problem is inside clogging, a technical wash is what actually restores breathing – fresh proofing on the outside does nothing for blocked pores.
- Wash with a technical cleaner made for membrane garments. Ordinary detergent and soap residue clog the pores further.
- Skip fabric softener entirely; it forms a film and smothers breathability completely.
- Run an extra rinse to clear all detergent residue.
- For heavy soiling: one wash is not always enough – a second round is often what lifts ingrained body oils.
- Then check the outside with the drop test. If water does not bead, the jacket also needs fresh proofing.
Prevent the membrane from clogging again
Most of the clogging comes from the body side, so that is where you prevent it. Wear a moisture-wicking base layer – it soaks up body oils and sweat before they reach the membrane. Wash the jacket before it gets truly filthy rather than waiting until it looks grey, and never store it dirty over a season, because that lets the grime set. Go easy on deodorant and sunscreen right before putting the jacket on, since these settle into the pores easily. A membrane kept clean stays breathable far longer.
When should you send the jacket to a professional?
If the jacket is still clammy after a correct wash, if you see signs of delamination – bubbling or a membrane that is flaking off – or if the taped seams are lifting, the jacket should be assessed by a professional. The same goes for expensive, technical shells you would rather not risk. We clean by garment and care label to lift what clogs the pores, re-proof the outside if the drop test fails, and can look at seams and repairs at the same time. Delamination is a repair question, not a washing one. You order online, and you see the price before you order.
You see the price before you order.
Frequently asked questions
Is a clammy jacket the same as one that leaks?+
No. A leak is water coming in from outside. Clamminess is usually sweat that cannot escape because the membrane is clogged inside or the outer fabric is wet. Both are solved without a new jacket.
Does proofing a jacket that won't breathe help?+
Only if the problem is outside wetting out. If the pores are clogged inside by body oils and dirt, you have to wash – proofing the outside does not open the inside.
Can I wash away delamination?+
No. Delamination, where the membrane bubbles or flakes off, is damage, not dirt. Washing does not help; it is a question of repair or retiring the garment.
How often should a membrane jacket be washed?+
More often than most people think. Body oils and sweat build up inside and clog the pores, so a regular technical wash keeps breathability up. Do not wait until the jacket looks dirty.
Rather have us handle it?
You see the price before you order.