Testing Páramo Analogy Waterproof Clothing: How Well Does It Work for Rain (and Wind Shells)?

[Stephen Seeber]

Companion forum thread to: Testing Páramo Analogy Waterproof Clothing: How Well Does It Work for Rain (and Wind Shells)?

An in-depth analysis of Páramo Analogy Fabric to see how it performs in wet conditions.

[Jerry Adams]

Really interesting.  You are very good at digging into technical problems

I have been experimenting with some related ideas.

I made a jacket from rsbtr wpb fabric.  It isn’t very breathable but it’s very light weight.

In medium rain, medium exertion, 50F, it will get wet on the inside, I assume from sweat that didn’t breath through the wpb fabric.

Then, that water gets my nylon shirt wet.  Also, I have pockets inside that touch the water inside the wpb.  The contents of the pockets get wet.  I wear a fleece hat and it does not get wet

I think the fleece hat is hydrophobic which prevents water from getting through.

So, I took some polypropylene fabric from the fabric store and sewed onto the pocket between it and the wpb.  Also, I made a shirt from the polypropylene fabric.  Polypropylene is hydrophobic.

I wore that in similar conditions and my pocket stayed dry, and my shirt stayed dry.

I need to test that better.  The winter ended and now there isn’t enough rain. I need to see if my results are repeatable and test in more extreme conditions.

My jacket uses 2.5 layer wpb and has a lining at Hood and shoulders. I need to make that with polypropylene.  And maybe some other shell fabric.  Like you have talked about.

I wonder what fabric would be best for the shell. I’m surprised how little HH it needs to be based on your test.

Maybe a shell from polypropylene would be good, doesn’t need any DWR.

A question I have about DWR is how long does it last in the rain?  My rsbtr starts getting out after an hour or so.  My neoshell wpb (that you recommended to me, thanks) doesn’t wet out.  Except I need to test that better when it rains again.

I haven’t seen any studies about this.  You did post a link to some studies that test how DWR survives washing.  By the military.  That is very important, especially for the military that washes their clothes.

My rsbtr jacket was wetting out very quickly, so I washed it and applied DWR restorer and now it’s much better.  It would seem that if the DWR gets dirty it will lose a lot of its repellency

Why wouldn’t you just use polypropylene which is permanently repellent, rather than a DWR that isn’t durable?  I think the fluoridated DWR theoretically works better than polypropylene.  It’s energy is more or the angle between the water drop and the fabric is greater or whatever.  And it pollutes the environment and possibly poisons me.

I have so many questions…

[Stephen Seeber]

Just to provide a little credibility, I cut a piece out of an old black umbrella to measure the hydrostatic head.  The answer: 243 mmwc, about the same as the Paramo jacket. Think about that when you are dry under your umbrella in the pouring rain. I wanted to clarify the opening photograph.  Those photographs were to illustrate the amount of fabric expansion that occurs during the hydrostatic head test.  The fabric was not a Paramo jacket.  It is a piece of fabric someone sent me to test. Another fun fact: while I was testing the umbrella fabric, I thought I would test a two-layer Frog Togs I had laying around.  It is polyethylene on the outside over a layer of polypropylene.  I expected it to have a low HH because it is a non-woven with very fine fibers.  If failed at about 2800 mmwc. Surprisingly high.  It didn’t actually leak the required 3 drops.  The fabric split under the pressure and produced a large stream of water through the opening.

Jerry, you asked too many questions, so I will answer what I can at another time.

[Jerry Adams]

Yeah, you seem to have some questions yourself you’re pondering

Your argument that you only need a low HH is reasonable.

I like your observation that the HH test stretches the fabric, which makes holes in the fabric bigger which causes more water to flow through.  It seems like that test concept isn’t good.

[Jeff McWilliams]

Interesting write-up.  I’m heading to Iceland in 1 day, and the weather forecast in the highlands is almost consistently 50’s with a bit of light rain each day.  This would seem to be the ideal weather for a Paramo.  Similar to UK weather?

At 16.8oz, the Paramo jacket tested is heavy compared to most US standards for a heavy rain shell let alone a lightweight one desired by backpackers.  (All of MontBell’s rain jacket offerings weigh less than 12oz)  The current Paramo men’s Velez jacket is speced at .605kg = 21.3oz.  Even heavier.

In 2011, Will Rietveld wrote an article for backpackinglight where he performed real world testing of rain shells to see how their breathability stood up to actual human use vs just looking at the numbers.  It would be interesting to see an updated version of that test using the latest from Paramo, Montbell (Super Dry-Tec), GoreTex 3L, NeoShell,  Columbia Outdry Ex, etc

There was a time when I recall Paramo sold a version of the jacket where the shell and the pump liner were separate items, so that the pump liner could double as a lightweight base layer or mid layer.  Looking at their current lineup, that no longer appears to be the case.  Or perhaps that’s the Enduro Windproof Jacket and the Enduro Fleece.  These items weigh .393kg and .436kg respectively, resulting in a system significantly heavier (and probably warmer) than the Paramo Velez.

[Jerry Adams]

In my experience, in the 50s, I’ll sweat.  The less I wear the better.  Thin jacket and shirt for example.  Maybe even just a shirt and don’t worry that it gets wet.

It seems like paramo would be better in colder weather

[Jeff McWilliams]

You’re probably right, Jerry.  Especially moving uphill, with a pack on.

 

[Mole J]

Jeff. 50’s °F (10-15° C) is warm for most people to use Paramo for activities with much exertion.

When considering the weight and warmth of Paramo, it should be understood that it is 2 layers of fabric, so more like a windshirt and light micro fleece in warmth levels than a single shell waterproof.

Even in the 40s I would rarely be wearing anything other than a t-shirt base layer if hiking in my Paramo.
Myself, I would also only to be choosing paramo if it was consistently wet or regularly showery, and I can wear it continuously.

[Andrew C]

So interesting. I’ve had my eye on Paramo for several years but the price has kept me from experimenting. But the take away seems to be that Parammo’s secret cause is not the outer shell layer but the pump layer. I don’t know if there is anything quite like it, although your photo looks not unlike alpha direct. I assume alpha direct isn’t treated to achieve the hydrophobicity of Paramo’s pump layer. Even is alpha isn’t the correct physical structure to achieve the same, why hasn’t polartec of some other manufacturer attempted something similar.  I know Paramo, while not delicate, requires more maintenance which may be anathema to the American market, but a a hydrophobic alpha fabric could be an interesting fabric all on its own.

[Haakon R]

The timing of this article and companion thread is quite interesting.

For the longest time I didn’t quite buy the marketing and functional description of Paramo’s Analogy waterproof concept.
But then again I have colleagues in the rescue service that swear it’s the best waterproofs they’ve tried – which I consider a very reliable source, so there was always this curiosity toward the fabric and doubt of my own assessment.

I’m not sure Paramo has ever had official distribution in Norway, my SAR colleagues got theirs during a exchange program with Scottish SAR some years before I joined, so that’s maybe 20 years ago.
This lack of availability has made the cost and difficulty of entry too hard to justify considering my rather lukewarm expectations.

This evaluation changed somewhat last fall/winter, when I came to a realization.
For my daily commutes (walking about 5km each way) I typically wear some type of active insulation to avoid getting cold, but weather changes fast around here, so rain, sleet or down right blizzards are not uncommon travel companions. This means I quite often have to throw a WPB on top of my active insulation jacket – which in turn makes me overheat in no time.
Thinking about how I could solve this, one idea that popped up was the fabric I never could justify: Analogy. In this use case it didn’t matter that they’re known for being a bit warm, as I need the insulation anyway. And due to the limited time I need to be outside – it also doesn’t bother me if they don’t quite live up to their stated performance.
Maybe I could buy a Paramo because I actually needed a Paramo, and not just to satisfy my curiosity? This was enough of an excuse to commit to some more research. Models, sizing, anyone else have experience from similar use cases?
Not all my findings where positive, and especially with regards to sizing. One poster on a UK outdoor forum described them as dog walking clothes for short and fat people. For someone tall and skinny like me, that’s not off to a great start :D
With the uncertainty regarding sizing and the added complexity of ordering from abroad, I didn’t go through with it last year.

Now, compared to how long I’ve had a curious eye on Paramo, last fall is like 10 minutes ago. And now I see this article and forum thread on BPL the same day YouTube feeds me an Engearment video about Paramo, and also informing that they’re establishing US distribution.
US distribution isn’t going to help me, but it’s at least a good sign to see that they’re expanding their distribution. Reading Stephen’s test is also quite encouraging, and could be enough to make me decide it’s worth going through the hassle of ordering from the UK.

[jscott]

Is a hydrostatic head what happens when you rub a ballon in your hair and it stands up on end?

I have so many questions too. None that are relevant but still…

[Stephen Seeber]

Hi Andrew:  Thanks for reading.  Let me clarify.  I think the real secret sauce is the fairly tight weave of the outer fabric, along with the Nikwax DRW treatment of both the outer shell fabric and the pump liner. At this point, I think of the pump liner as a fail-safe layer. I expect that Alpha Direct could perform a similar function to the pump liner. It is more or less equally hydrophobic.

[Stephen Seeber]

In the article, I erroneously described the shell material as nylon.  It is actually polyester.  Sorry for the error.  The use of polyester makes sense here.  Untreated polyester has a contact angle of 72.5.  Nylon 6-6 has a contact angle of 68.3. Polypropylene has a contact angle of  102.1.  A contact angle greater than 90 degrees is considered hydrophobic.  Polyester is more hydrophobic than nylon. So, even as the DWR degrades on the Paramo shell, the polyester fiber resists wet out better better than a nylon fiber would.

[Phil J]

I’ve had a paramo for many years. It would not be my choice for a multi day trip where I expected heavy rain on a daily basis. For me it scores far better than membrane garments in arctic climates for activities like ice climbing, skiing or dog sledding. In such climates membrane garments are not as good as fabrics like ventile or paramo analogy. but marketing hype and brand loyalty lead many folk stick with their waterproof breathable membranes.

[Andrew S]

As always, VERY interesting!  Leads to many, many questions, etc.

Starting with the last chart (figure 12):  First, understanding from the article that with zero wind, rain falls vertically at up to 20 mph, this suggests that it hits horizontal fabric (like the top of a hood) in torrential conditions (100mm/m2/hr) with a pressure of 175mm/m2 – not quite enough to go through the Paramo fabric, which is nice.

But what about at higher altitude?  Can’t rain fall faster when air is thinner since it’s air resistance that limits the speed to 20 mph?  How much faster?  (Or maybe lower air pressure prevents the formation of such large drops??)

Also, the lines in the chart show the pressure when hitting a vertical surface, but that is not where the rain will hit with the highest pressure.  It will hit hardest where the surface is perpendicular to the direction of travel, like somewhere on a shoulder or hood.  With 50mph wind and big drops falling at 20mph, the perpendicular speed would be 54mph, which doesn’t really change the conclusions – you’ll still stay dry with 15mm/m2/hr of rain, you’ll still be wet with 100mm (unless you have a membrane).  But with 20mph wind and 20mph drops, the drops are hitting a perpendicular surface at 28mph.  In a torrential rain, that might be 250mm of pressure, which is greater than the fabric’s HH.  So it seems you’d get wet.

But one needn’t give up on the Paramo approach just because of this, or even because of 50 mph torrential rain.  There are are least one or two companies making clothing with Paramo’s inner layer and a Ventile outer layer.  And standard 200g/m2 cotton Ventile is said to have an HH of 600mm.

However, there seems something strange about the two lines on this chart.  The blue line, for torrential rain, shows much higher pressure.  But both lines are for the same size rain drops hitting at the same speed.  The difference between these big-drop versions of torrential rain and heavy rain (the other line) is that with torrential rain, more rain drops hit more places in the same amount of time.  But that doesn’t make the individual rain drop impacts any more forceful, so why does it matter?

On the one hand, 100 drops each hitting a different mm2 on the same cm2 at the exact same time will press that cm2 100 times as hard as a single drop hitting it, maybe stretching the fabric enough to open a gap.  On the other hand, even a single drop would stretch the mm2 it hits as much as the 100 drops stretch the entire cm2.  So why wouldn’t the single drop also get through?

Maybe, at least in test conditions, it’s because the area of fabric around the mm2 that can help absorb the impact is a lot larger in proportion to the mm2 than the area around a cm2 that can help absorb 100 impacts.  But if that’s it, then I would think the increase in pressure that comes from more drops per second per cm2 should not increase linearly with the number of drops.  Furthermore, in real life, the whole face of the jacket facing the rain is under pressure, so it’s not clear any help will come from neighboring fabric.

This brings up something else:  If I understand correctly, in the test, the fabric is stretched taut.  But even so, it will have some give to it.  And unless I’m mistaken (and I might be – I’m not an engineer or a physicist) the force imparted by a drop is not (directly) determined by how fast it is, but by how quickly it slows down.  If it slows down literally instantly (which I guess is impossible), then it would hit with infinite Gs.  But if instead of being stretched across the pan, the fabric were sitting on the surface, it could not give as much and the drops would slow down much more quickly, thus hitting with many more Gs.  This would be like a hood that wind and rain have already pressed against a bald head.  Whereas a rain jacket lying on top of a plump, puffy jacket might give drops a nice soft landing.  All this suggests to me that if the rain is almost hard enough to penetrate Paramo in the test conditions, there are real world conditions in which weaker rain would make it though – and also in which much stronger rain wouldn’t.

And then there’s how the pressure in the test was measured.  I understand it was done my measuring how hard a stream of water pushed down on a scale per cm2 of the surface of the plate or panel that the stream pushed down on.  That tells you the average.  But the stream didn’t push down on the entire surface. In some places, it probably didn’t push down at all.  In others, it pushed down more than average.  If this is right, and the fabric didn’t let water in, then it suggests it can stand up to even harder rain than measured.  BUT, perhaps individual drops of rain that collectively pushed down as hard on the same, say, cm2 push down even harder on the exact spots they hit?

In a different Backpacking light forum discussion, someone posted a calculation of the force of a rain drop in terms of HH.  The calculation took into account that the entire weight of a drop is apparently initially born by a small surface area at the tip and concluded that with drops sped up by high wind, you need around 15,000mm to stay dry.  I believed that for a long time.  Then I realized that most tents don’t have a HH anywhere near that, and yet they keep you dry … .  But maybe there is still something to it?

Anyway, back to the fabric.  It would be interesting to know how much of Paramo’s HH is from the outer layer.  In part because of a question about what exactly the inner layer does.

As I recall, the clear message from Paramo’s website is that the inner layer isn’t (just) hydrophobic, it is directionally wicking.  I understand that to mean that if you expose the inside to water, it will pass to the outside with little or no pressure, whereas water that drips on the outside will not make it to the inside absent lots of force.  Is that true?  And if so, is it really a unidirectional fabric, or is it just because of higher temperatures inside the fabric than outside?  To what extent would other (wicking) fabrics perform the same way when worn?

And if it is true, then maybe we should think about performance in torrential rain in a different way.  Maybe what matters isn’t how much pressure it takes to force water through (in which case how hard each drop hits seems to matter), but how much water the inner fabric can move from inside to out per m2 per second (in which case how many drops you get per second can matter a lot, even if they are slow).

I once came upon what I think were European waterproofness standards for workwear.  There were several levels, and I think the highest required over 5 or even 10 thousand HH.  Was that because the tips of rain drops hit really hard?  And/or because of pressure from pack straps and knees?  Don’t know.  But the description I read mentioned something about higher HH being necessary for prolonged exposure.  Why?  With something like Paramo it could be for for the reason I just mentioned – probably.  But why would this be relevant with a membrane?  Can lower HH membranes let water pass through when they are wet out?  Or … ?

Finally, why wear Paramo?  Maybe it blocks the rain whenever Gore Tex does, with the exception of the fiercest storms.  But the MVTR number isn’t better than the best membranes, is it?  And I understood from the text that the CFM isn’t anything special either.  So what’s the benefit?  Paramo says that not only can vapor escape, as with a membrane, it also sends liquid water from inside to out, unlike a membrane.  Does it?  And how often does one care (if one is not in a canoe or the wind isn’t blowing water though cuffs and everywhere else)?  Or maybe the (one way) wicking simply makes it FEEL dry (which is of course nice).  Which brings us back to the question whether wearing a similar layer under a traditional wpb layer would have the same effect.

[Andrew S]

Phil J, why would it or ventile be your choice in arctic climates?

[Stephen Seeber]

Hi Phil:  Thanks for your comments. As I mentioned in the article, I have never worn one of these jackets in real life.  As I also mentioned, I hoped members would share their experiences. I hope we get some more user reports.

[Andrew S]

Haakon, you explained how you are interested in Paramo because you want to keep dry without overheating.  This brings me back to Stephen’s also fascinating test and analysis of wind shirts, a garment type I’ve never understood.  Especially given Stephen’s earlier test showing that MVTR ratings are a better indication of how much moisture stays inside than CFM.  And since the best wpb fabrics match the MVTR of any wind shirt except maybe airshed, which barely blocks wind, why not just use a wpb jacket?

My hypothesis was that even if Gore Tex lets more moisture out, and even if it keeps you equally cool due to the heat the moisture takes with it (thought it might not – greater airflow with a wind shirt might cool you a bit more, and I did have some questions about the conclusion that a boundary layer means there is minimal real world air flow through a wind shirt … ), but anyway, even if it matches the wind shirt in these ways, the wind shirt might FEEL drier.

I suspect the key to not feeling like you are overheating so quickly is that the fabric absorbs and/or wicks moisture, even it it doesn’t wick it to the outside.  Gore Tex can’t do that.  (Though perhaps with the right liner fabric … Arcteryx has a Gore Tex ski jacket with a synthetic flannel (yuck!) lining.  Get’s great reviews.  Maybe this is why.)

And maybe this subjective benefit would have practical benefits.  If the inside of a jacket gets clammy and sticky enough, maybe some water will condense on other layers.  And maybe the jacket’s MVTR will drop.  Maybe this doesn’t happen so much or so quickly with wind shirts?  Or with Paramo??

[Andrew S]

P.S.  Haakon, if fit is an issue, there is at least one company making custom made Analogy garments.  Pretty sure they’re in Scotland.  If memory serves, they just might be on the Isle of Skye.  (Like you, I’ve been curious about Paramo for some time.  I’ve been planning to visit one of their shops in the UK when I’m there a month from now.)

[Andrew S]

Where did the edit button go???  Still so many typos in my posts :-(

[Stephen Seeber]

Hi Andrew S. I think you exceeded the questions per post limit.  I will see what I can do. Clearly, calculating static force or kinetic force from a raindrop under lots of conditions is very complex and beyond the scope of what I can do here. A vertical surface is used here because it is based on calculations produced for building walls in rainstorms from ASTM. I agree with you that a drop falling vertically and hitting the top of your hood will have more energy.

While writing the article, I had a chat with ChatGPT. I asked it how much force a large raindrop exerts on a horizontal surface and then, how that changes with wind, when hitting a vertical surface. If you wish to review the calculations, you can ask the same question to ChatGPT. Here are the answers: Vertical force for a large raindrop traveling at 9 m/s is .0302 Newtons or 3 GF (grams-force).  3 GF is the same force as, say, a 3-gram stone resting on the ground under Earth’s gravity.  So, a pretty small number.  Now, take the drop and blow it into a vertical surface with a 50 mph wind.  The answer becomes 8.24 gf. Still, not a huge force. If 8.24 gf occurs over 1 cm2, this is equivalent to 84 mm water column.  Well below the HH of Paramo.

Concerning the impact of elevation on drop force. After a couple of rounds with ChatGPT , this is the result. It is small. At 12000 feet the raindrop should be traveling at 25 mph. The kinetic energy at sea level will be 1.35 mJ. At 12000 feet it will be 11.25 mj. That converts to 11 mm wc and 17.2 mm wc.  I have been rained on at 12K and 0K and can’t say have noticed a difference on my head. I have noticed the difference at 12 K when Gropple and static electricity discharges hit my head. Then I ran down the mountain, out of the cloud I was in.

To put this in perspective, I tested an umbrella for HH and listed the answer above.  It was a little higher than the Paramo.  So, think of a storm that you have experienced.  An umbrella may blow out and you may get wet from side winds, but have you ever seen a raindrop cut through an umbrella?

As far as Paramo’s claims of directional wicking, I find the claim curious.  The pump liner is coated with DWR. That should mean that initial absorption of liquid water into fibers cannot happen. Without initial absorption, wicking cannot occur.  Also, the DWR coated fibers are hydrophobic.  For capillary action to occur, the fibers must be hydrophilic on their exterior.  They aren’t.  Now, if your moisture is in vapor form, that will flow through the pump layer and then the outer layer, as long as there is sufficient vapor pressure differential.

That is my answer limit for now, you are welcome to post other questions.

[John Conley]

I’m very impressed with the results of these tests. I’ll be considering Páramo products as an alternative to waterproof rain gear.

Here’s a comment/observation: Since the accumulation of penetrated water seems to be at the lower hem (a situation I’ve noticed in most “waterproof” rain jackets), I wonder if a product modification (perhaps a DIY homemade mod) to incorporate drain holes along the bottom of the lower hem might not be helpful.  These could range from simply snipping through the bottom of the hem fabric, to installing small grommets. Obviously, the result, assuming the modification worked, would be the accumulated water from the pump liner would drain out the holes (and I guess annoyingly running down your legs!!). But that might be preferable to ending the day with the lower hem of your jacket still wet.

[Tjaard Breeuwer]

Haakon,

I am tall and skinny too, and have been very happy with my custom Nikwax Analogy garments made by Cioch Direct, indeed, in Scotland.

I think they could work very well for your use case. As conditions change, it’s easy to adapt the warmth provided, by opening venting like pitzips, cuffs and front zippers. Because you are venting through both your “windshell” and your “super thin fleece layer” at the same time, in the same spot, you get a lot of cooling.

I don’t often use them for backpacking type outings, because of the weight and the fact that (some) insulation and the shell are combined in one garment, so can not be separated.

I am thinking again of getting a separate liner, and combining it with a nice windshirt.

The other advantage for regular use (I use the pants as my fall/winter several days a week), is the easy care, repair and modification. Seams are not taped, so any mods or repairs are simply sewing.

And finally, there is the comfort and silence of the flexible, supple fabrics without membranes.

[Phil J]

Tjaard,

as you must know the Paramo system isn’t limited to its two part fabric system and hydrophobic mid layer garments. I’m not sure to what extent current designs incorporate another feature they had in early models, namely the use of removable foam strips between the two fabric layers. I think this was incorporated into the back of some jackets and the seat area of salopettes. So, their designs incorporated a kind of interoperability not seen in other outdoor clothing makers, designs best suited to snowy winter conditions in my opinion where comfort and function take precedent over the need to keep rain out. It might all seem to be a bit over designed to the armchair critic but the only way to find out is by real world use and testing. Personally, I’ve never gone all in with a complete clothing system but UK mountain rescue teams seem to be happy with Paramo functionality.

[jscott]

https://thedaily.case.edu/rubbing-balloon-hair-make-stick/

tough crowd. who might think the scientifically minded have no sense of humor?

hey a neutron and proton and a broke rabbi walk into a bar. The drinks charge is neutralized. Turns out there’s free energy after all! The Rabbi wobbles out of the bar giving his blessings all around.

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