Interesting comments in this blog. Not too much new, but still some interesting observations which brings me to the following questions: * if paclite has a thicker PU-layer, why then can it be more breathable than XCR since the diffusion speed of vapour through the PU-layer is inversely proportional to the layer thickness? * if windstopper has no PU layer, then it is in fact nothing less then the first generation of gore-tex, right ? In which way then does windstopper differ from the gas-permeable gore-tex used in tents, bivy's, ...? The only way a gore-tex membrane can be gaspermeable is by having no PU-layer, which is exactly what windstopper is. So the same product, having different names. * a need for better DWR's: exactly my idea. I still don't understand why Gore's so strict on which DWR's can be used with the gore-tex mebrane. Patagonia's Deluge gets some good comments but can't be used.
Interesting article in "Trail" a couple of months back where they found that "Comfort" fabric conditioner is nearly effective as a DWR as Grangers etc ( and massively cheaper of course). Has anyone else tried this method ? BTW NONE of the aftermarket DWR's gave a satisfactory performance after ONE weekends use !
*note to oneself - start a thread on relative performance merits of Lenor versus Comfort*
Also re:steaming clothing, my £50 Gill jacket for cycling regularly steams in winter months. Does this mean I have particularly breathable jacket for the price or its not waterproof ?
Yep, I guess it's not earth shattering stuff, but it's interesting to see such a graphic representation of air permeability and the way different fabrics work. Paramo passes air at a lower pressure than eVENT btw, but is also a lot warmer, which is an issue for some.
As far as Paclite goes, the inner layer isn't pure PU as far as I can see, but whatever it is, it's highly hydrophylic, so it sucks moisture into it. Now, I don't think that it is any more breathable than XCR in strict terms. What I reckon is happening is that initially, excess moisture is absorbed rapidly by the inner scrim - the grey stuff - keeping you dry it's then released gradually across the membrane.
In other words, it's acting as a buffering layer. Berghaus did some testing with Ken Ledward using moisture sensors inside a Paclite jacket and what happened was that on uphills, the atmosphere inside the jacket became more humid, then on the flat and downhill, as activity levels dropped, the humidity cleared.
The buffering layer just gives you a buffer, a sort of 'breathing space' if you like. What I've found with Paclite, which fits in with this, is that if you cane it hard enough with constant effort - running for example - then it's comfortable for about 20 minutes at which point, all hell breaks loose, the inner wets out and it becomes suddenly very uncomfortable. That would happen much faster with XCR, the difference is the buffering layer.
An analogy might be a bucket which is being filled with a one pint glass of water and emptied at the same time, with a half pint glass. Initially the bucket holds the water and even though you're putting more in than you can take out, it doesn't overflow.
If you go on putting full pints in for long enough, the half-pint bailer can't match it and the bucket overflows. On the other hand, if you stop putting water in, or only put, say a quarter of a pint in, the bucket gradually empties. So... on undulating terrain, Paclite does actually work quite well, it's less good with continuous high tempo activity which is the equivalent of constantly adding full pint glasses of water, if that makes sense.
That's just a theory, but it seems like a reasonable one to me and is born out by the way the fabric works in practice.
Windstopper? Yes, pretty similar to the original Gore-Tex I think. As far as the air-permeable bivvy fabric goes, yes, I think it must be similar, but Gore does have different membranes and it may be that the bivvy bag version is more expanded, so has larger pores as well as, obviously, different scrim and face fabrics.
And like I said, I do think more durable DWRs are the future and I know that the fabric companies are working on them. Seems logical to me that a good starting point would be a ,material that's naturally hydrophobic in the way that polypropylene is perhaps treated with something that works at the level of individual fibres like Epic's DWR.
In the end it's more an interesting sideline to the really important thing of getting out there and just doing it, but sometimes understanding how kit works helsp you use it more effectively and contributes to a more comfortable or even safer time on the hill, if that makes sense :-)
Yep, nothings beats some time on the hill, but nevertheless, these kind of discussions can be quite fun. Now about paclite, as far as I know the hydrophilic layer on the inside is a hydrophilic PU-layer in which carbon particles have been mixed to add some durability. This way the normal tricot can be replaced. The fact that the layer is hydrophilic, combined with the inclusion of carbon particles, explains to me why it absorbs moisture and why it can act as a buffer. But I don't know if this is actually different from the tricot used in 3-layer waterproofs which has some kind of buffering function too (perhaps less efficient as the carbon/PU-layer although I'm not sure about this based on my experience with paclite/XCR combo). Still, if the PU/carbon-layer in paclite is thicker than the Pu-layer in XCR, one would think that the breathability of XCR is a bit better since the thicker hydrophilic layer, the lower the diffusion through the layer (give that the composition of the layer is a constant). Ofcourse, one cannot forget that the tricot in 3-layer jackets probably reduces breathability explaining perhaps why RET-values for paclite are lower than for 3-layer XCR. Added proof for this could that RET-values for 2-layer XCR, which I believe is being measured without the inner liner, is equal or lower than paclite. The bucket explanation seems very reasonable to me although I would add another component. Hydrophilic layers have a tendency to get more and more effecient when humidity rises. So the higher the humidity, the better a hydrophilic layer will pass the moisture from one side to another (I believe Mountain Hardwear's Conduit is marketed this way: the harder you sweat, the better it works). Adding this to your bucket story, this would mean something like the bucket being made out of a slightly stretchable material and the weight of the added water stretches the bucket, making the hole at the end larger and that way increasing the capacity of the half pint bailer (which makes it no longer a half pint bailer isn't it).
BTW, the increasing efficiency of a hydrophilic layer increasing the breathability of the layer is an interesting aspect if you compare it with eVENT. Because while it looks like a interesting property, it means in the first place that you have to sweat a lot, getting a clammy feeling first, before the layer starts to function really well. eVENT is not hydrophilic but has the advantage that it works equally well at high and low humidity. Perhaps this looks like a disadvantage compared with hydrophilic layers but it actually means that eVENT works 100% from the beginning, taking it longer for humidity to increase and taking it longer to get a clammy feeling. Moreover, it also works in the other way. Once you get a clammy feeling in an eVENT jacket, it will dry rather quickly since it works equally well at high humidity levels as at low humidity levels. But because hydrophilic layers work best a high humidity levels, it will take longer to dry once humidity has lowered substantially.
It's possible that the carbon in the Paclite layers also acts as conduit down which water can pass, thus increasing the rate of diffusion. Similar to Triplepoint Ceramic.
A better bucket analogy might simply be a hole in the bottom of the bucket. As you add more water, the level rises and so pressure increases, and thus the outflow rate increases.
Merino wool provides an analogue to the behaviour of Paclite, too. The wool fibres are able to absorb water to a certain point, after which they are overloaded. This tallies with people's findings with merino being overloaded after prolonged, heavy exertion.
better DWR's will eventually exist when we find an alternative to nylon for jackets - nylon being hydrophilic. So we make jackets out of a fabric that likes water, simply because it is so damn durable for the weight.
Jon, Have you tried any synthetic down products in the bubbler?
Primaloft gave me a "cocktail shaker" which I could trap a little square of Primaloft & a pool of about 150ml of water in. Inverting it proves that it will withstand a certain level of water pressure - yes, with no fabric at all! I wonder if it would fail blowing bubbles through it? It is impressive stuff.
To answer Danny's point, we already have several alternatives to using nylon (and polyester) - polypropylene and siliconised fibres (from cotton to nylon.) Primaloft's siliconised polyester insulation called 'One' is a good example. A brand called Epic make all sorts of siliconised fabrics, but may be hard for you to find.
Due to cost factors, the whole fabric is treated rather than individual yarns. This gives it low porosity, but the denims are great for less active use in cooler weather.
Why haven't we seen hydrophobic polypropylene & siliconised fibres used as face fabrics? The clue is in Arc'teryx's synthetic down products being a lamination of Gore and cheaper Primaloft Sport, rather than Primaloft One - cheaper and Arc'teryx don't normally go in the same sentence! Primaloft Sport is like One but without the silicon treatment. It is near impossible to laminate either silicon or polypropylene to a membrane without loosing porosity (i.e. breathability) and a host of other desirable characteristics. You could go back to hanging membrane liners... but that's another story.
I wonder whether the Paramo swatch would work while it was under compression and with a depleted DWR coating?
In reply to Peev, the chances are that your Gill jacket is made from a fabric with a microporous hydrophobic coating. Interestigly enough when you put such fabrics over the eVENT bubbler they also allow air to pass through. Although a lot tend to be 2.5 layer and have a thin protective coating which allows less air through.
Re the DWR thing on PTFE laminates, we've been speaking with eVENT quite a lot on this one. One problem that they are trying to overcome is that fabrics that have a very top top DWR don't stick to PTFE to the standards that they require. Their DWR is still good, but it is stoping them from using a super-duper DWR if such a thing exists. This may well be the same problem with Gore being picky over the DWR.
As a whole and with exception of Epic DWR needs to be improved massively. There are some excellent fabrics out there, but their performance is often let down by the DWR's durability. Apparently polyester is stightly better for attaching DWR molecules to, and thicker heavier yarns have more points to bond to once you've already taken up some of the bonds with colour.
I agree with Jon, fabric manufacturers perhaps need to look at it from a different angle i.e. not use a hydrophilic yarn in the first place or something completely different, maybe with the structure or shape of the yarn/fabric to allow it to bond well on once side and push water away on the other.
Self cleaning or abrasion resistant dwr would also be good as these are the 2 key factors for reducing the repellency. Dirty, abrasive rucksack straps are the number one repellency killer.
The humidity side of things is also an interesting one. Event works regardless of humidity levels inside and outside the garment. Like a cup of hot coffee in a sauna steam will still come off of the coffee regardless of the amount of steam in the room. Whereas hydrophilic fabrics actually rely on the humidity gradient to work, which incidently is not directional i.e. it can work both ways, so if you put a pin hole in a hydrophilic membrane and it's raining water can be pulled back in by the hydrophilic properties (obviously depending on the gradient ;-))
Skin is the best waterproof breathable fabric that there is. But I wouldn't suggest running around the Lakes in the buff.
Oh, I forgot to mention the carbon in Paclite that Tom mentioned. We were all given the marketing spin about durability... NONSENSE!
The carbon has been put in to stop us noticing the unsightly yellowing that the membrane experiences over time! All marketing - Gore are masters of the dark art!
I'm looking forward to Schoeller making their NanoSphere fabric an option for use as a face fabric. Or maybe this is the "super-duper DWR " Julie has been talking about that won't adhere well to PTFE? Maybe The Avatar can enlighten us?
(NanoSphere is, to quote Scholler "a natural non-stick and self cleaning process transferred to the surface of the fabric by means of nanotechnology." It is a biomimicry concept based on the lotus leaf effect.)
Just to let you know that apparently Gore is going to respond to the article, probably early next week, so it'll be interesting to see what they have to say. I'm not saying, btw, that the bubbler is a definitive test of anything, but it's interesting looking at differerent fabrics regardless of what it tells you.
I've not tried Primaloft or similar in the bubbler btw. I did put some Polartec Powershield in it. That's the stuff claimed to be 98 per-cent windproof with resulting enhanced breathability, and the air fair bubbled through it at speed. Interestingly, if you sucked instead of blowing, the water bubbled through the other way. I'm guessing that points to a deliberately perforated membrane.
As far as needing to get out more goes, yep, that's why I'm going out now :-)
Nextec's EPIC and Patagonia's Deluge DWR treatments are both use silicone encapsulation of the fibres. Which, as other have mentioned, isn't that easy to glue.
I wonder if the process could be performed after lamination...
PowerShield is a matter of some dispute. Some say it has a membrane, some say it's just glue.
The most convincing story I've heard is that PowerShield was a three-way development between Malden (Polartec), Tweave (makers of stretch face fabrics) and Dartex Coatings (makers of glue). Bascially, you apply glue onto one of the fabrics, which either naturally has gaps, or is applied in a way to create gaps, and then laminate the face to the inner fabric.
Result: stretch woven outer glued to fleece inner, with 'engineered' wind resistance.
Based on what I've found, I have enough reason to believe that Powershield is a glue or foam which is put through a series of rollers to make it air permeable. At least the first Powershield fabric, used by Arc'teryx in its Gamma SV, was a three-way development between Malden, Tweave en Dartex Coatings. I suppose that more recent versions of powershield also use face fabrics other than those of Tweave.
Interestingly enough, soft shells are often made out of fabrics which are even more hydrophilic than those of waterproofs because of their high content of stretchfibers. Once the DWR of my powershield jacket starts to fail, the fabric seems to act like a sponge. At least some manufacturers are starting to make soft shells made out of polyester with mechanical stretch.
About DWR's: is Lowe Alpine's Dry Yarn technology also based on individually coated fibers? Or is it something else. I remember reports of Triplepoint Ceramic performing better under rainy conditions than gore-tex, probably because of the dry yarn technology.
Powershield and Windbloc ACT are Dartex inventions and could be described as punctured membranes. They laminate with an indirect coating process - it isn't the lower quality direct coating process associated with poor quality "coated" waterproofs.
Indirect coating is where a polymer (PU in the case of breathable waterproofs) is layered (from a trough, not sprayed) onto a moving belt of heat-proof paper. The PU doesn't stick to the paper but acts as fairly strong glue to fabrics - no other ingredients are required.
The flat paper belt enables accurate measurement of the thickness and consistency of the layer, not possible on direct coating because the applied polymer sinks between the yarns taking the shape of the fabric's surface. After an initial oven curing the fabric is laid on top, the paper is then pealed away before a further lamination can take place. Two ply indirect coating also has the advantage over a two ply direct coating in that it retains a relatively flat surface resulting in less points of wear.
As I understand it, what Dartex have done with Powershield and Windbloc ACT is lay a thin web, possibly a very open knit, onto the paper before layering on the PU. After the PU goes through the first oven for curing, the web or knit is pulled off leaving spots of PU on the paper.
PU is stretchy stuff – in fact Lycra/Spandex is a form of PU. Thus your stretch wovens will tend to absorb lots of water and take ages to dry and the same will happen in a waterproof with a hydrophilic PU layer.
Whether you have a eVENT of PU waterproof you are always relying on DWR for breathabil¬¬¬ity. But once DWR fails, or the humidity inside (from sweating) or outside the waterproof has been high, a PU layer will take much longer to dry out than microporous membranes like pure PTFE.
We may see more fabrics available using conjugate polyester/corterra/(maybe nylon) fibres as an alternative to hydrophilic Lycra. Commonly described as "3D" fibres, they have a spring like form. These are more expensive yarns and harder to weave or knit. I suspect they have lower abrasion and pill resistance because of their shape.
I'm not sure how Unitika's Dry Yarn and Schoeller’s 3XDry work and if they are truely special. For over the counter choice, Mark Taylor of the Performance Clothing Research Group tells me that Grainger's Fluoro-based DWR is more effective than the silicon based Nik Wax.
This isn't the most interesting subject is it... what's the weather like over your way?
