M50 rain jacket

Jerry,

I tested Thru-Hiker M50 in a report I posted to this forum in 2011. The areal density was .7 oz/yd2; the air permeability was 73.2 CFM; and the HH was 70.30 mm H2O. Based on those numbers, M50 would be an excellent fabric if you wanted to make a UL wind shirt for highly aerobic activities. For use as a rain jacket, it would be a very poor choice.

In my same series of postings I also tested the closely related Thru-Hiker M55 which has similar areal density but, a much higher HH as is required for a pseudo rain jacket. The areal density was .75 oz/yd2; the air permeability was 3.45 CFM; and the HH was 667.84 mm H2O. If you used this material over a cushioning base layer (Cap 4 gridded fleece as an example) it would perform similarly to the Paramo-Furtech-Buffalo products as rain wear.

Without the cushioning base layer, even M55 would leak in moderate to heavy rain. You can read the marketing literature for Paramo-Furtech-Buffalo in an attempt to understand this approach to rain wear. Alternatively you can look in most physics books for an explanation of the “Impulse-Momentum form of Newton's Second Law”.

thanks

I'll have to look in my physic books for Impulse-Momentum form of Newton's Second Law – or wikipedia : )

hmmm I wonder who sells M55? I seem to remember thru-hiker used to but not any more

I've noticed that my shoulders and head get wet much more than everything else. Maybe put eVent over those areas and M55 everywhere else.

Where can one buy event fabric?

Along the lines of what Richard was saying, its important to note that if you go the Paramo/Furtech route, its important to treat that cushioning layer with a high quality DWR. I don't know yet, but I suspect that a thinnish layer of polypro base layer might be as effective and without needing a DWR treatment. Well I plan to test it in any case.

I bought some eVent from BPL, but that was a one time deal

questoutfitters has similar WPB. or owfinc.com

Yeah I've seen some of those fabrics on some of the DIY sites, but wasn't aware they had event equivalents. Before I knew any better, I bought the lightest polartec power shield fabric version from Quest O.F.'s and made a flip over bug/rain bivy. Now I consider it too heavy and bulky to be practical. I do like the combo of breathability and serious water resistance though.

Quest has WPB that may not be as good as Goretex or eVent:

2.5 WPB – 2.5 to 2.7 oz/yd2

Hyvent is 1.8 oz/yd2, membrane has a special print matrix so it doesn't require lining, but I wonder how well that works

3 layer HyVent is 2.45 oz/yd2

But M50 and M55 are like 0.7 oz/yd2, may actually be more breathable or less insulating so you won't overheat and sweat so much

My eVent jacket wets out at shoulders and hood so I'm thinking of making a new one. Maybe experiment with lightest weight fabric.

I just got M50 for quilt and it sheds water very well – but it's new

There have been a lot of threads on this, usually started by folks trying hard to lighten their packs. Please consider that a reliable WPB rain top is the best protection against hypothermia, or 'exposure.' No one dies from being soaked, they die form 'exposure.' If you're going to spend on anything, the rain top is a good choice.

I enjoy fooling around with fabric offerings from Quest and others, but I do not fool around where my rain top is concerned. If you can test and verify the DWR, vapor permeability and water resistance of a material, which I doubt, I suppose an MYOG rain top is OK, but it won't be as light as the welded seam ones now being made.

In addition to Richard Nisley's post, please read Alan Dixon's article here:
http://backpackinglight.com/cgi-bin/backpackinglight/00316.html

A less than 2 oz 'eVent' material was sold on this site, and Jerry's report is that it is not working in a rain jacket. There are several possibilities – here are some:

It may be the eVent cannot function as designed in such a light layup that none of the responsible manufacturers use.

It may be that BPL was 'mistaken' about the product.

Worse yet, evaluations of new WPBs on this site in the last couple years indicate that eVent is marketing its product to manufacturers under other names, and not taking direct responsibility, as Gore does, for the use of its product. Also, these same reviews found wide variations in the performance of eVent rain tops.

If more 'breathability' were a priority for me, I would buy an event jacket from the most reliable sources – example, the REI jacket – it is called 'Kimtah' or something like that. I printed out all the BPL articles and studied them repeatedly, and while they were not unanimous on all points, it was clear that some eVent products, being marketed as eVent or something else, were no better than GoreTex offerings, and sometimes worse in terms of breathability and/or water resistance. I do plan to take a look at the Patagonia M10 if and when the hype and price come down; but some posters have had problems with the durability of Patagonia DWR, once a staple, not to mention the DWR from Rab, also once thought to be consistently reliable.

No doubt all of this is frustrating, but wishing won't make it otherwise. Here's a list:

BPL articles on rains shells and pants: 2010-2013

Rain Pants Article – June 2012

http://www.backpackinglight.com/cgi-bin/backpackinglight/rain_pants_sotmr_2012.html

2012 State of Market

http://www.backpackinglight.com/cgi-bin/backpackinglight/ul_wpb_jackets_sotmr_part2.html

http://www.backpackinglight.com/cgi-bin/backpackinglight/ul_wpb_jackets_sotmr_part1.html

Will's articles 2011

http://www.backpackinglight.com/cgi-bin/backpackinglight/waterproof_breathable_technologies_part3.html

http://www.backpackinglight.com/cgi-bin/backpackinglight/waterproof_breathable_technologies_part2.html

http://www.backpackinglight.com/cgi-bin/backpackinglight/orwm_2011_wrapup_waterproof-breathable_technologies.html

ID pullover 10 oz?

http://www.backpackinglight.com/cgi-bin/backpackinglight/integral_designs_pullover_review.html

If you spend a lot of time studying these articles as I did, I really think you will agree with my conclusions. Alas, they are pretty inescapable. Because you may get only one chance to find out if your rain top is reliable in extreme weather, this is not an area for much experimentation, IMO.

“Impulse-Momentum form of Newton's Second Law”

Okay, I think I get you

if you put a cushioning layer underneath the fabric, it takes longer for a raindrop to go from it's falling speed to zero speed, then it puts less force on the fabric, so the fabric needs less hydrostatic head to keep the water from going through the fabric

that's pretty cool

okay, I did some experimenting

first, if the fabric is too stiff, then it won't deform when hit by a drop, so I used a scrap of M50 which is about the least stiff I have

then, I put some over 200 weight fleece with the M50 on top and dropped a few drops of water on it

if there was like a wrinkle of M50 sticking up, then it was pushed down maybe 1/8th or 1/4 inch – so that would work

if the M50 was flat against the fleece, the fleece didn't compress so the M50 didn't seem to move at all so I don't think that would have worked. Maybe a high speed camera would reveal more? Maybe it moved a little?

if I put a down filled sample under the M50, then the M50 did move so that worked, the down is much more compressible than fleece.

my conclusion – the underlying material has to be very soft and easily compressed

if you had grid fleece with M50 on top, then there would be air space between ridges so if a drop fell in between ridges that would work. I suppose even if the drop fell directly on a ridge, it would still spread out and push down the fabric so that might actually work too

What's your opinion? Do you think this principal is valid? Are there any measurements that verify? It seems like you would have to have drops of water falling on fabric, you couldn't just have a column of water with static pressure applied.

But I don't really want a compressible layer, because I'll sweat regardless, and adding a compressible layer will add insulation so I'll sweat more

On the other hand, where the fabric hangs vertically, which is 90% of the area of the jacket, the fabric will deform if hit by a rain drop regardless.

Have to ponder this some more

Jerry,

At…ta…boy… You now understand the "secret" for designing a UL DIY WPB rain shell, without a coating or membrane… its the liner.

The "non-secret" part of the design is to use a woven fabric that has a high HH. There is a reasonably close inverse relationship between a fabric's CFM and HH. Blow through various fabrics to find one that satisfies your criteria for low CFM, weight, aesthetics, and cost.

Alternatively you could start with a high HH / Low CFM commercial windshirt and then experiment to find the "secret" optimal base layer for the level of rain pressure you want to protect against. The fabrics in the ORC PCU L4 windshirt, the 15 denier segments of the Montbell Mistral windshirt, The North Face Verto windshirt, the Mountain Hardwear Ghost Whisperer windshirt, the newest Epic Malibu windshirts, or the newest Patagonia Houdini windshirts are a few examples that will protect against much harder rain, using the same base layer, compared to a M50 windshirt or an old Houdini windshirt. These materials have relatively low CFM / high HH (<=1,000 mm H2O).

So I looked at Nikwax, Paramo, Buffalo, Furtech, Cioch websites. None of them explained much.

wikipedia "nikwax analogy" was much better

it said the outer layer slows the rain down which is as close to Impulse-Momentum form of Newton's Second Law as anyone came

it also said they have a pump layer that relies on the effect that water flows in the direction of increasing diamter

it also mentions that with all those layers it adds insulation which can cause you to overheat especially if it's not too cold and you are exerting – that's my big problem with rain gear. venting helps but is only a partial solution – that's my experience also.

if you're not sweating, then you don't need wicking or a pump

maybe it's naive to think that it's possible to not sweat

I'll have to experiment like you suggested…

Samuel, have you tried a Paramo/Furtech or equivalent type of WPB? I hear they are quite popular in England and Scotland.

Jerry, I don't know if this helps you are not, but I have a Paramo "pump liner" that i purchased from Cioch. The fabric weighs less and is thinner than a 100 wt fleece (i'd estimate it at around 75 or so), made out of polyester that has been soaked in Nikwax, the outside of the fabric is sort of a soft, brushed, micro-fur like texture and the inside of the fabric is smoother/harder (not brushed) and if you look real close the pattern is like lots of vvvvv's stacked and repeating.

Apparently the differential between the larger threads/fibers on one side to smaller on the other side is what drives the "pump liner" effect. Pertex Equilibrium also uses a similar principle in it's fabric. Polartec powerdry does as well (but might be in the opposite direction?)

But I will stress again, I do think a good DWR treatment of the pump liner is also important to maintain full "Waterproofness and Breathability" of these ultimate wp*B* systems.

Anyways, there was a British guy (forget his name), who experimented with just using a pump liner like mine that he also got from Cioch, in combo with a light weight and breathable windshirt. He found it did work, and was noticeably cooler and a bit lighter than than the lightest full on Paramo jacket. He wrote an article and made a video on it, if i come across it again i will share a link.

Personally, I wouldn't use this unless we're talking a cold rain. If's it a warm rain, I would just take off and pack most of my clothes, put very thin synthetic shorts on (i have a pair of 1.7 oz supplex nylon running shorts), and enjoy the nice shower :)

Paramo user here, fire away with any questions.

How much does it weigh?

Do you sweat while wearing it?

I have the Valez adventure Light Smock.

I will weigh it in but I think its about 600g. I am not too concerned about the weight as I never intend to carry it, I see it as 3 in 1 items as it does the job of hard shell, windshirt and mid layer. I have never sweated much in it either hiking, skiing or snowshoeing, if I get too hot I open the side vents, pull down the centre zipper and pull up the sleeves. I find it far more comfortable to wear than my Event Hard shell.

I normally only use it below freezing.

600 g

21 ounces???

that weighs as much as insulated layer and outer layer combined

(I wish we'de just bite the bullet and get rid of this ridiculous "British" system of measurements)

I can see how that would be really useful in very cold and wet conditions when just base layer and jacket are insufficient

My Xl weighs 618g, I use it conjunction with a pair of Paramo Cascada Trousers (670g in Xl) which are in the heavier more durable favour of Paramo.

I only bought the set at Christmas and have used them on about 5 weekend trips, 3-4 days hikes and about 10 days cross country skiing.

Thinking about it now I used them in 45f with Cap 1 under them and was fairly comfortable, most use was between 20f to -5f where ai wore a Mec T2 hoody. I know a lot of folk back in the Uk/Ireland that swear by Paramo/Cioch/Furtech.

Hope this helps.

As said the weight does not bother me (or others) as its not intended to be carried.

I work off grams and Kilos as I am from Ireland, but we do still use pounds/ounces for some things which is a bit weird.

I was sceptical about Paramo for 15 years or so until I was in an independent outdoor shop in the Uk at Christmas and got talking to the owner about it, he said to try it for a day hike and if I was not happy he would refund me.

Oh forgot to say the liner is about the equivalent warmth as Cap 2

"As said the weight does not bother me (or others) as its not intended to be carried."

If you wear weight it still has a negative effect – makes your back, legs, feet sore. But 600 g is probably not noticeable.

"I work off grams and Kilos as I am from Ireland, but we do still use pounds/ounces for some things which is a bit weird."

metric is making inroads here very gradually. many drinks are sold by the 1/2 or 1 liter for example. and scientists and engineers use metric pretty much totally, until they get off work.

I really don't think the weight is noticeable as before using Paramo I would of worn a 150g windshirt, a 300g mid layer and then a 300g hard shell if it was raining or if the snow was very wet.

They two major adamant aged to me are the outstanding breathability and not having to stop to remove/add clothing, I would equate the comfort of Paramo to wearing Capilene/r1 and a wind shell.

At work metric is used but then you go for lunch and everyone (scientists included) use imperial :-

Jerry,

Not sure if you have seen this Paramo article by Chris Townsend, well worth checking out if you have not.

http://www.backpackinglight.com/cgi-bin/backpackinglight/paramo_clothing.html#.UiJHjsu9KSM

"Samuel, have you tried a Paramo/Furtech or equivalent type of WPB? I hear they are quite popular in England and Scotland."

No, as I checked into the weights, and they are quite heavy compared to the 8.5 oz XL top that I can hike moderately in all day in the rain without getting wet, from inside or out.

Samuel, the pump liner i have weighs 8.4 oz. A lot of people bring both a light weight windshirt and dedicated rain gear at the same time anyways.

So it's not really much of a "weight penalty" if i bring the pump liner and my windshirt, and it's a heck of a lot more flexible/adaptable since i could use them separately. That, and it breathes better than any other WPB system out there.

But yeah, a full/non separable Paramo or Furtech jacket is pretty heavy, and doesn't make a lot of sense.