Reproofing rain gear: DWR, wetting out and when a shell is finished

Durable water repellent is a surface treatment that makes water bead and roll off the outer face of a fabric. It is not the waterproof layer, and it is not permanent. When it fails, the face fabric soaks up water, breathability collapses, and you get wet from your own condensation while the membrane underneath is still doing its job perfectly. Most jackets sent back as leaking are wetting out.

What DWR does, and what it does not do#

A waterproof shell is a stack. The outer face fabric is a woven nylon or polyester that carries the DWR and takes the abrasion. Beneath it sits the waterproof layer, a membrane or a coating, and that is what stops liquid water. Inside there may be a knit backer or printed pattern holding the membrane off your skin.

DWR changes the surface energy of the outer face so that water cannot spread across it. Water has a surface tension of about 72 millinewtons per metre at 20 degrees C, which is high, and a treated surface with a much lower surface energy forces droplets into beads with a contact angle above 90 degrees. Beads roll off, and the fabric between the yarns stays full of air.

That air is the point. The repellency is not there to keep water out, since the membrane does that. It is there to keep the outer fabric dry so that water vapour from your body can keep crossing it. The relevant measurement is not hydrostatic head but evaporative resistance, RET, measured on a sweating guarded hotplate under ISO 11092. Lower is better, and published values for shell fabrics commonly run from below 6 for the most breathable laminates to above 20 for cheap coated fabrics. Our guide to rain jackets and breathability works through what those numbers mean in use, and waterproof ratings explained covers the millimetre side.

Why a wetted-out shell makes you wet from the inside#

Vapour moves through a membrane because there is more water vapour on the warm inside than on the cold outside. That gradient is small in absolute terms, and it takes very little added resistance to stall it.

When the DWR stops working, water spreads into the spaces between the yarns of the face fabric instead of beading on top. The fabric goes dark and heavy, and a continuous film of liquid water now sits directly against the outside of the membrane. Vapour that would have evaporated away has nowhere to go, so it condenses on the inside of the membrane instead and runs down the lining. The wearer feels cold wet fabric on their arms and concludes the jacket has leaked.

Two clues separate them. Wetting out gives dampness spread evenly across the shoulders and arms, worst where a pack strap presses. A genuine leak gives water in one place: a seam, a zip, a worn patch at the hip belt.

A saturated face fabric also holds water that evaporates and cools you, so the chill from a wetted-out shell in wind is a real thermal load. Our layering guide puts numbers on the heat balance behind that.

The sink test: wetting out, leaking, or delaminating#

Ten minutes at a kitchen sink will tell you which of the three you have.

1. Beading test. Run the tap gently over the shoulder, forearm and hood of a clean, dry jacket. Water should form beads that roll off. If it soaks in and the fabric darkens, the DWR is finished on that panel. Compare panels: shoulders and forearms fail first because pack straps and sleeves see the most abrasion.
2. Push test. Hold a wetted panel taut with one hand behind it and press with a finger from the outside for 20 seconds. Wet fabric that stays wet only on the outside is wetting out. Water that transfers to your fingers behind the fabric is a leak.
3. Seam check. Fill the sleeve or a section held as a bowl with water and leave it for two minutes. Seepage along a seam line means the seam tape has lifted, which is a repair job rather than a reproofing job.
4. Inside inspection. Turn the jacket inside out under good light. A healthy inner face is uniform. Bubbling, flaking, a shiny sticky feel, small lifted patches or a persistent musty smell that survives washing are all delamination or hydrolysis.
5. Flex test. Crumple a suspect inner panel in your fist ten times and look again. A layer that is breaking down will shed flakes or show new lifted areas.

A jacket that passes the push test, the seam check and the inside inspection but fails the beading test is a reproofing job and nothing more. That is by far the most common result.

Why renewal is more frequent than it used to be#

Repellent chemistry has changed. Long-chain fluorinated treatments produced very low surface energy, repelled oils as well as water, and lasted a long time. Those compounds are persistent in the environment, and PFOA and related substances are now listed under the Stockholm Convention and restricted in many markets, so the industry has moved to fluorine-free chemistries based on silicones, hydrocarbon waxes and dendrimers.

The physical consequence is straightforward. Fluorine-free surfaces sit at a higher surface energy than the fluorinated ones did. They repel water, whose surface tension is around 72 millinewtons per metre, perfectly well. They do not reliably repel oils, whose surface tension is typically in the 20 to 35 range, which means body oil, sunscreen, insect repellent and road grime contaminate the surface and defeat it much sooner.

So the practical difference is not that modern jackets are worse made. It is that the treatment on them needs washing and reactivating more often, and re-treating more often than the treatment on a jacket bought a decade ago. Plan for it as routine maintenance in the same way you plan to wash a down bag, rather than as a warranty issue.

Wash first, treat second, heat third#

Dirt blocks a treatment from reaching and bonding to the fibre, so a shell must be clean before anything is applied. That single step also solves a proportion of DWR failures on its own, because a mildly contaminated finish often recovers with a wash and heat and does not need re-treating at all.

1. Empty and close. Pockets empty, main zip and pocket zips closed, hook and loop tabs fastened, cuff and hem cords loosened.
2. Clean the machine. Run a rinse cycle first if the drawer has held ordinary detergent or fabric softener. Residues in the drum will land on the shell.
3. Wash. Use a technical cleaner, warm cycle as the care label allows, and two rinses. Never fabric softener.
4. Heat and retest. Tumble dry on low for about 20 minutes, then repeat the beading test. If beads return, stop. You have finished.
5. Treat if it did not return. Apply a wash-in or spray-on treatment as described below, on a clean and, for spray-on, still damp garment.
6. Cure the treatment. Most need heat to bond: typically 20 minutes of tumble drying on low, or ironing on a low setting through a cloth or a piece of paper if the care label permits ironing at all. No heat means no durability.
7. Retest. Sink test again. Patchy beading means an uneven application, and a second light coat on the failed panels fixes it.

Wash-in or spray-on. Wash-in treatments go through the machine and coat every surface of the garment, including the inner face. That is fine on a simple unlined shell and quick to do. Spray-on treats only the outer face, which is what you want on anything with a lining, a mesh backer or insulation, because a repellent finish on the inside can slow the movement of moisture away from your skin. For a lined jacket, an insulated jacket or a garment with a soft backer, spray-on is the better choice. The same logic applies to insulated pieces, which is why our down washing guide steers away from wash-in treatments entirely.

How often to re-treat, by use#

Intervals scale with abrasion and contamination, not with calendar time. A jacket in a wardrobe does not lose its finish, a jacket under a pack every weekend does.

The trigger is the sink test, not the schedule. Use the table to decide when to run the test.

When the shell is finished#

Three failures are terminal and no treatment addresses any of them.

Delamination is the membrane or backer separating from the face fabric. It shows as bubbles, lifted patches or a rippled inner face, often starting at the inside of the elbow.

Hydrolysis is the chemical breakdown of a polyurethane layer by water, accelerated by warmth. It shows as a sticky, tacky or flaking inner face and a musty smell that survives washing. It is a storage failure as much as a use failure: a shell packed damp and left in a warm loft is the classic case, which is why gear storage matters more than most people assume.

Abrasion through the face fabric. Once the weave is worn down to the membrane, that membrane has no mechanical protection and fails there shortly. Patches buy time.

Seam tape lifting is not terminal. Iron-on seam tape or a liquid sealer fixes it, and it is worth doing before writing off a sound jacket.

Common mistakes#

Treating a dirty jacket. The treatment lands on the dirt and comes off with it. This is the single most common reason a reproof does not work.

Skipping the heat step. Many treatments need heat to bond and align. Skip it and the beading looks fine on day one and is gone within a week.

Using ordinary detergent or softener. Both leave a surfactant film that attracts water, which is the opposite of the goal.

Assuming a leak. A jacket that lets you feel wet across both shoulders in steady rain has almost always wetted out. Run the push test before deciding.

Using wash-in on a lined or insulated garment. It coats the inside face too. Use spray-on.

Reproofing a delaminated shell. New DWR on a jacket whose inner face is flaking is money spent on a garment that is finished.

Frequently asked questions#

Why is my waterproof jacket wetting out but not actually leaking?#

The durable water repellent on the outer face has worn off or been contaminated, so the face fabric absorbs water instead of beading it. The waterproof layer underneath still works, but a soaked face fabric blocks vapour from escaping, so sweat condenses inside and you feel wet. Wash the jacket, heat it in a tumble dryer for about 20 minutes, and re-treat only if beading does not return.

Do I need to reproof a new rain jacket?#

Not usually, but check it after 10 to 15 days of hard wear. Fluorine-free treatments are less durable than the older chemistries, and shoulders under pack straps can stop beading within a season of heavy use. A wash and a heat cycle often restore the finish without any product at all, so try that first.

Is wash-in or spray-on DWR better?#

Spray-on for anything lined, insulated or backed with mesh, because wash-in coats the inner face as well as the outer and that can slow moisture moving away from your skin. Wash-in is faster and gives even coverage on a simple unlined shell. Both need the heat step afterwards to bond properly, and both need a clean garment underneath.

Can I put my rain jacket in a tumble dryer?#

Check the care label first, since some laminates specify no tumble drying. Where it is permitted, about 20 minutes on a low heat setting is the standard way to reactivate or cure a water repellent finish. If tumble drying is not allowed, ironing on a low setting through a cloth or a sheet of paper achieves the same thing, provided the label permits ironing.

How do I know if my jacket is delaminated?#

Turn it inside out under strong light and look at the inner face. Bubbles, lifted or rippled patches, flaking material, a sticky feel, or a musty smell that survives a wash are all signs the laminate or coating is breaking down. Crumpling a suspect panel in your fist ten times and re-inspecting makes early delamination easier to see.

Why did manufacturers stop using the old water repellent chemistry?#

Long-chain fluorinated compounds such as PFOA are persistent in the environment and are now listed under the Stockholm Convention and restricted in many markets. The replacements, based on silicones, hydrocarbons and dendrimers, repel water well but do not repel oils, so skin oils, sunscreen and grime defeat them sooner. That is why re-treatment intervals are shorter than they used to be.

How often should I wash a rain shell?#

Roughly every 10 to 15 days of active wear, and whenever it stops beading. Under-washing is the more common error: people avoid washing a shell in the belief that it damages the fabric, when accumulated body salts and oils are what kill the repellent finish. Use a technical cleaner, never a standard detergent or softener, and follow with a heat cycle.