UKC

Goretex Jacket wetting out on shoulders

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 jj-1992 02 Feb 2020

Hi

My effectively new Rab Ladakh Jacket (bought September, used a dozen times) has this weekend started to wet out on the shoulders and around the hips.

This is where my rucksack sits so wondering if this could be causing the issue maybe? although seems wierd as everyone wears a rucksack in the same place so shouldnt be causing any issues???

Ahhh annoying.

Going to take the jacket back to the shop this week but wanted to have a wider opinion of why it would happen, as my previous ME jacket did a very similar thing but all over not just the shoulders.

Post edited at 17:29
 marsbar 02 Feb 2020
In reply to jj-1992:

Was it wetting out when you were wearing the rucksack?  

Have you tried wearing it in the rain without the rucksack?  

Either the rucksack is preventing the goretex from breathing which means it is your body's moisture that is making you wet or it's not and the rucksack has damaged the fabric in those places.  Or its just a coincidence. 

Post edited at 20:37
OP jj-1992 02 Feb 2020
In reply to marsbar:

I was wearing the rucksack when it was wetting out, but tested it from dry without after and it is still wetting out.  At least it is now, had not noticed it before now though.

It is only wet on the outside so don't think it would be moisture coming out.

Post edited at 21:37
 Billhook 02 Feb 2020
In reply to jj-1992:

If it was wet on the outside only, when you were not wearing the sac, then there's no problem.

Marsbar is right.  If its wet on the inside when wearing a rucksac then its because the fabric can't breath with the straps on your shoulders so it condensates there.

Post edited at 21:46
 olddirtydoggy 02 Feb 2020
In reply to jj-1992:

There's a great article on the website Section hiker called 'Why does DWR suck?' I'm assuming they still use this method of making water bead on jackets as it's been a while I've bought one.

 TobyA 02 Feb 2020
In reply to jj-1992:

> It is only wet on the outside so don't think it would be moisture coming out.

I don't think that is what "wetting out" means then. So you jacket isn't actually leaking? It's just no beading up like new in wear areas?

 Andypeak 02 Feb 2020
In reply to jj-1992: 

6 months with a gortex jacket before it starts wetting out is about standard. Wash with Nikwax and continue as normal

 marsbar 02 Feb 2020
In reply to Andypeak:

And warm (not hot) tumble dry if possible.  

 GHawksworth 02 Feb 2020
In reply to TobyA:

That is what "wetting out" means but people often associate it to failing. It is not failing. All that's happened is the straps have worn the DWR off. Without DWR, any and every jacket will wet out.

To "wet out" is the saturation of the outer (face) fabric of the garment. ie, no longer beading. The reason this is significant to modern garments, especially jackets, is that the breathability in wetted out areas is reduced to 0. Like us, garments can't breathe through water and wetting out is essentially waterboarding for your jacket. That's why DWR is seen to be so essential, as the beading allows the membrane in the garment to "breathe".

The reason I wouldn't worry about it wetting out where your rucksack straps sit is simply because the breathability is reduced to nearly 0 by having your straps there in the first place. Your jacket can't breathe through straps, so why does it  need to breathe on your shoulders?

To replenish the beading, simply apply any "proofer" spray or post wash kit, like TX direct.

Only when your jacket gets wet on the inside, whether its from leaking or condensation through excessive wetting out, would I worry about the integrity of the jacket.

 neuromancer 03 Feb 2020
In reply to jj-1992:

A while back someone who knew a lot more about breathable membranes than I did (worked in materials) suggested that water could be, without too much difficulty, forced through a breathable membrane in the reverse direction. This was, once the jacket had become saturated, a reasonably common thing to happen underneath rucksack straps - i.e. wet straps, compressed under pressure against a saturated jacket would act like a pump to slowly force water through the membrane backwards.

Is this horse-shit?

 marsbar 03 Feb 2020
In reply to neuromancer:

I'm not a materials scientist, but as I understand it the membrane isnt one way.  It has "holes" too tiny for liquid water to get through but vapour can get through which is how it works because we are warm and rain is not.  

I could be wrong but that's how I remember it.  

 MischaHY 03 Feb 2020
In reply to neuromancer:

This depends on the metric 'hydrostatic head'. With Gore Tex membranes the hydrostatic head is 28,000mm or higher, hence why they're willing to guarantee waterproofing. 

More info here: https://www.ultralightoutdoorgear.co.uk/what-is-hydrostatic-head-i1245 

 MischaHY 03 Feb 2020
In reply to jj-1992:

Taking it back will be a waste of time - you just need to spray the shoulders with TX-Direct to renew the DWR coating: https://www.nikwax.com/en-gb/products/productdetail.php?productid=16 

The Ladakh has 70 denier patches on the shoulders so I'd be amazed if you'd managed to wear through them already. 

Many people have the same experience as you've realised, because wearing a rucksack rubs the shoulders rather a lot. 

Basically, the jacket is fine. Give it a spray so it beads again, and crack on. 

cb294 03 Feb 2020
In reply to neuromancer:

This. All such membranes work because the hole size and wetting properties of the pores are chosen so that water in the gas phase will pass through easily, while liquid water will require pressure to get through the pores. This is why the water resistance of membranes is measured by their "hydrostatic head", i.e. the height above which a water column will generate enough pressure to force liquid water through the membrane. This is under lab conditions, after even a little wear, this value will drop.

In practise, pressure from the rucksack straps will squeeze water trapped beneath them (e.g. in the wetted out fabric) through the membrane.

Reinforcement patches will protect the membrane, not the water repellent in the fabric, for a while.

CB

1
 oldie 03 Feb 2020
In reply to cb294:

> This. All such membranes work because the hole size and wetting properties of the pores are chosen so that water in the gas phase will pass through easily, while liquid water will require pressure to get through the pores. This is why the water resistance of membranes is measured by their "hydrostatic head", i.e. the height above which a water column will generate enough pressure to force liquid water through the membrane. This is under lab conditions, after even a little wear, this value will drop. <

For my own curiosity. Do you know why the value drops with wear? In my imagination dirt might block access to the pores and if anything inhibit water passage. Presumably the pores must increase in diameter or become more hydrophilic.

 Frank R. 03 Feb 2020
In reply to oldie:

As far as I understand it (having read some research papers on WPB materials, but not being a materials scientist myself), it's mainly because dirty membrane fibres get more hydrophilic from the deposited salts and dirt.

The main way a microporous* membrane works - keeping the liquid water out while (hopefuly) passing water vapour - is not because of any miraculous one-way Maxwell's demons or "pore size too small for liquid water" (like the marketing departments say), but because the membrane fibres are hydrophobic and any water droplet will have well enough surface tension to not pass through, unless overcame by the pressure. If it gets dirty enough, water can enter more easily.

*: like eVent, Gore-Tex (some of theirs add a nonporous polyurethane coating to protect the microporous membrane from getting dirty so easily, but that lessens the breathability) and others. There are also nonporous hydrophilic membrane technologies which work slightly differently.

Post edited at 14:02
 Siward 03 Feb 2020
In reply to Frank R.:

Interesting. Are they nevertheless microporous in the sense that there microscopic pores in the membrane, holes too small to admit a water droplet (unless under pressure)?

Does regular washing then, in detergent, really prolong useful life (of the garment, not oneself!) 

Post edited at 14:27
 Frank R. 03 Feb 2020
In reply to Siward:

Sorry, I was going to write a lengthy reply at first, but then I found this very good (even if older) UKC article and associated discussion says it all:

https://www.ukclimbing.com/articles/features/waterproof_breathable_fabric_-...

Re: Washing: I guess it depends on the manufacturer's instructions, type of the membrane and fabric. eVent (microporous ePTFE) still recommends regular washing. I wouldn't certainly wash it after every use but never washing it could worsen not only the "breathability", but the waterproofness as well - at least for the microporous ones. I remember reading that the early, very first alternate (ones without PTFE, since PTFE has the benefit of being naturally hydrophobic and very stable*) electrospun microporous membranes were less tolerant of washing, since they relied on added-on DWR-like hydrophobic treatment of the membrane itself, which could wear out after so many washing cycles, thus a compromise might be better with some fabrics. The newer ones are allegedly much better in that regard.

*: ePTFE, a fluoropolymer, is very stable (apologies to any chemists here for my layman explanation), so most damage from washing would be probably just mechanical or by contamination from stuff like perfumes and fabric softeners that coat it and degrade the hydrophobicity. The obvious downside to fluoropolymers is that many of the chemicals used in their preparation can be very persistent, bioaccumulative and toxic. DuPont's Teflon factory used to dump them a lot into the local wastewater, although after so much public scrutiny a lot of the industry practices changed. Even Gore-Tex seems committed to move to PFC-free garments now (EU regulations might have had something to do with that ).

Post edited at 18:25
OP jj-1992 05 Feb 2020
In reply to jj-1992:

Thanks everyone for your thoughts.

Update, I have washed and reproofed with TX-Direct and this seems to have done the trick and it is beading again. 

Annoying that I had to do it so soon but at least it is back to what it should be doing.


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