Questions about putting some eVent fabric onto Cuben MLD SoloMid for venting

Justin,

It might work out cheaper and lighter to sell
the Solomid and ask Ron Bell can he make a new one to your specifications.

It would be worth giving Ron a call.

I don't think there would be significant breathability if the entire tent was eVent – it's just not very breathable. Good for clothing though.

If you want a vent, it should be big, like maybe 1 square foot, and no fabric at all. But in my experience, even that doesn't work very well, I need to have a vent of 1/4 the surface area of the tent – that is, open the door.

You have a Cuben Solomid? Nice! I wouldn't want to ruin it by altering it.

"… eVent – it's just not very breathable."

Are you referring to Cuben/eVent, or traditional 3-layer garment eVent?

Yeah, i got it used from here awhile back–twas a good deal.

Jerry, i was under the impression that eVent being slightly air permeable, was pretty breathable as far as WPB stuff goes…at least in the context of moisture vapor generated while at rest or sleeping. I know we exhale a lot, which really adds to the load vs wearing eVent clothes while resting, but i'm not looking for perfect, just better. I think an all eVent tent would probably be awesome for condensation provided there is still a regular peak vent.

Anyways, there is still the top regular vent in my tent, and i'm sure some air movement from below. As far as ruining the tent, it seems like it would be an easy mod. Just cut out a piece of the cuben and sew, then seam seal/tape, the eVent fabric slightly overlapping same? If i'm missing something please let me know, i'm willing to learn and be wrong (i do it enough anyhow, especially so my wife tells me ;)

p.s. i'm looking for traditional 3 layer eVent material, not the cuben hybrid stuff.

Hi Stephen,

Thanks for the suggestion. Lighter most likely, cheaper probably not. I bought it used to begin with, i already have some silnylon 2nds, and i'm not looking for much eVent material. Maybe just about a yard to a yard and a half piece cut up in halves.

Since it's so light to begin with, i'm not worried about adding a little extra weight if it improves my tenting experience in the winter. Eventually, i'm looking to do some serious winter/extreme cold stuff.

I've "heard" that cuben is not ideal for winter/snow stuff because the snow tends to stick to the cuben material… so i've even thought of very lightly spraying the outside with some silicone spray to increase the slickness some. I know it won't last very long, but for a shorter trip should do the trick temporarily.

Justin, I am commenting based only on my use of event and experience with venting on shaped tarps. I have not tried what you suggest.

I think you will add some weight to a lightweight shelter and get little noticeable difference in performance.

I like event on my body for rainwear. But you are talking about venting your entire body thru one little patch of event. More importantly, you are talking about venting all of your breath and associated moisture thru this patch of event. I don't think it would vent particularly well even if you had a full event solomid.

I think a small open vent would have much better venting.

But if you do it, let us know how it works, because I am just giving you my educated guess.

Thanks Ben, i appreciate the feedback. Yeah, unfortunately it might be one of those things that's hard to be certain of without experience.

If i end up doing it, i will let people know how it goes.

yeah, let people know your results

WPB like eVent works on your body, where there is a temperature/humidity gradient from the inside to outside.

On a tent, you don't have the gradient so it won't work hardly at all.

At least theoretically : )

And you only need 3 layer to prevent body oils from getting on the membrane. For a tent, 2 layer would be sufficient.

owfinc.com had some eVent

Justin,

I say its still worth having a chat with Ron as he may have some pointers.

Best of luck with it :-)

"WPB like eVent works on your body, where there is a temperature/humidity gradient from the inside to outside.

On a tent, you don't have the gradient so it won't work hardly at all."

hi again Jerry, I thought that only applies to Gore Tex and PU based WPBs whereas because eVent is slightly air permeable it doesn't need the gradient difference as much? I remember reading some posts here where people talked about experiencing a stiff wind where in they felt a little bit of the air come through.

I was thinking recently of putting one patch near where my head would go and another near the apex.

I thought about Epic but I've heard it has some problems with temperatures near freezing, and vapour can and often does freeze in it for that temp. range. Plus, I won't just be using the tent in winter and Epic might not have enough HH for serious rain.

Thanks Stephen, may do that.

“I’m trying to turn my Cuben SoloMid into the ultimate winter tent”

From Ryan Jordan’s review of an eVent tent.

“eVENT fabric is not magic. In very cold conditions, interior humidity will cause frost buildup on the interior of the tent walls. Of course, we’ve yet to experience subzero conditions where this did not occur to some extent on every breathable fabric tent we’ve tried, including the Epic tents from Black Diamond.”

“However, the eVENT offers significant advantages over other waterproof breathable fabrics … in that the climatic range for which condensation does not occur when all vents are closed is significantly broader. Based on side by side comparisons of eVENT and Epic tents, where boiling a small cup of water inside the tent created an atmosphere of 100% humidity, we noticed significantly less condensation on the interior of the eVENT tent than on the interior of an Epic tent, when the outside air temperature was 20 degrees and calm.”

So even with 100% eVent, and a warm tent, ” … we noticed significantly less condensation…”. But not “… no condensation …”. With the larger volume of a ‘mid and colder interior temperatures, things can only be worse.

IMHO, I don’t think a even couple of square feet of eVent will make a significant difference. And although you might Reduce the condensation, you will still have to deal with it.

We’re a long way from winter, so please update this thread sometime in February.

[Edit to add: There are a couple of very light stoves out there…]

Hi Greg, thank you very much for the holistic info. Sounds like eVent patches won't make enough of a difference to warrant the extra weight.

So, i will scrap the idea.

Have you seen this? http://locusgear.com/products-2/shelter/khufu-event-ii?lang=en

You could always sell your Solomid and go for the all-eVent Khufu.

Hi Clayton,

Thanks, and no i have not seen that. Looks interesting, and i've heard good things about Locus Gear. 472 dollars for the 22 ounce tent is alright, but i'm short on funds, and probably could only sell the Solomid for around 200. Plus the colors are perhaps my least liked colors, heck i would go with bright sky blue before scarlet or black for a tent.

A very real concern with using an all eVent tent is what happens when the DWR fails? I imagine it soaks up a lot of water and gets rather HEV'AY? One of the nice things about cuben is how it doesn't ever seem to soak up water (though polyester does absorb a tiny, tiny bit of moisture).

The Solomid is $355 new in cuben, and unless yours is in poor shape or several years old, I would think that you could get about $300 for it this time of year. With MLD wait times back up to their usual 8+ weeks, the market on Gear Swap is hot for immediately available MLD 'mids.

Hi Clayton,

Good points and i appreciate the spirit of your reply, but problem is, i paid around 250 or so for it (i don't remember exactly how much now), and while i've only used it a few times since and it's in great shape, my conscience wouldn't let me charge what i paid for it, let alone upcharging.

In any case, there is still the problem of an all eVent tent getting wetted out and getting really heavy. Also, it's not going to dry out as fast as silnylon when it does wet out.

All, or mostly cuben is really nice in that regard. If i do the inner liner using the IR reflective heet sheet, i probably should have less problems with condensation anyways. I didn't experience much condensation in my combo Polycryo and Heet sheet tarp i made, even when i tried to pitch it as low as possible (and it definitely seemed warmer in cold temps).

Ok, as mentioned i ditched the eVent idea. I'm also ditching the heat sheets idea in favor of aluminized cuben. Richard's tests seem promising, and i'm assuming Nathan has done some of his own field tests (?). Recently i sold more stuff than i thought i would, so figure i could splurge on two yards of the above. Seems like it would last a lot longer and be a lot more tough than heat sheet stuff (it will be nice not having to worry about ripping and tearing it so easily).

I'm excited to test this stuff out in the winter in combo with the Solomid. Not sure how i'm going to set it up yet. I'm thinking velcro strips to connect it to the top and have it drape down a little (to have some air space between the Solomid and reflective cuben).

I will also add loops onto the reflective cuben piece to make it usable as a tarp, so for warmer weather i could put it over the solomid for shade/sun protection, or combine it with a bivy and ditch the solomid (though a 6 ft x 4.5 ft tarp isn't really big enough even for me and an all protective bivy in rain, i don't think. Maybe ok for emergency backup when the forecast looks good).

I measured a piece of aluminized cuben and even though it looks aluminized, the temperature difference was halfway between aluminum foil and regular fabric. Although that's a tricky measurement and I would like to see data from someone else.

Also, cuben is good for a tent where you want maximum strength for the weight. For a liner, you don't need the strength, so a "space blanket" would be better. Unless you don't care about cost.

Hi Jerry, did you see this thread? http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=88716

I'm looking for maximum durability (i don't like to use throw away materials, though i have before), and while you don't have to worry as much about a lining material, ime both regular space blankets and to a moderately lesser degree heat sheets, are pretty fragile from all angles.

Even if you don't make a tear or in the case of heat sheets stretch it out, the aluminum coating will fairly quickly start to rub off and/or oxidize, decreasing it's effectiveness. The beauty of the cuben stuff besides the tensile strength is that the aluminum is protected inside–so theoretically it's IR reflective capacity should last a lot longer and be much more consistently stable than space blankets or heat sheets.

As mentioned, i can also use it as an emergency backup tarp in combo with a bivy, when the forecast looks good. Normally cost is a big factor for me, but as mentioned i sold more stuff than i expected too recently. Speaking of which, time to go down to the post office and send most of that off!

Ciao

No, I didn't see that.

Interesting that the emmisivity was 0.41 for aluminum foil. Like Roger said, that should be very close to zero. Makes me question that.

I measured with a "torso simulator" which has a 50 W/m2 heat output like a human body, with some insulation on top, and aluminum on top of that, and measured the difference in temperature between the outside surface of the aluminum and ambient. This was on a clear night. Measured several times, approximate results:

regular fabric – 10 F
aluminized Cuben both sides – 20 F
Aluminum foil or space blanket – 30 F

Tricky measurement, I don't have a lot of confidence. The minimum temperature you can comfortably sleep at should be reduced by this amount.

This is a pretty small effect, you might not notice 10 F colder temperature. Plus, I think if it's windy the advantage goes away.

If you used a low emissivity liner and you got 20 F lower minimum temperature, it would probably weigh less to have a sleeping bag with a little more insulation.

An old idea for winter tents is to make an inner tent with very light breathable upper and waterproof floor. The solomid would function as a fly and structural support. The way it works is that air flows mostly between the inner tent and outer tent (solomid), so you'll be warmer. It should also reduce condensation considerably, especially if you raise the bottom of the mid off the ground to increase ventilation.

The ideal fabric would be a tightly woven windproof material, momentum, pertex, etc. DWR probably is not needed; plain 1.1 oz ripstop would work but be heavier. A cheap version could be made with the lightest silk habotai, but would probably be less warm because it's less windproof.

I'd just hang it from the mid so that it can be cinched up to near the mid for space or lowered to reduce volume and increase warmth for sleeping.

You could also add a strip of breathable nylon around the bottom of the mid. This would let you set up the mid right against the ground for better wind strength and to reduce snow blowing in, while giving more breathability. It'd also give more interior volume which is helpful in winter camping.

Even if Richard's instrument needed to be re-calibrated, if he measured the various different materials around the same time frame, the relative difference between them could still be accurate even if the exact temps or values are not, right? If that is the case, then the aluminized cuben tests pretty well.

Btw, when you say you tested aluminized cuben, was it the newest version or some older version?

I don't expect my body heat to be enough to make much of a difference by itself, but as i've mentioned a few times before, i like to bring a couple of smaller beeswax candles for light, and i suspect if i can get the tent pretty well tight with little wind coming in, the combo of my body heat, two candles, double wall design and IR reflective liner might raise the temp significantly enough to make a difference between comfortable outside one's quilt/bag or not during more extreme cold temps.

Thank you for the tip Walter. I've thought of trying a set up like that before. The only thing i don't like about that idea is that using a breathable material, especially like nylon or silk, it will tend to soak up moisture some.

Awhile back, i made a largish tarp out of a combo of polycryo and heat sheat reflective material. I took it out a handful of times during winter. It seemed when i pitched it low and tried to block the openings as much as i could, because there was a small air gap between the polycryo and the heat sheet in most areas (the materials were only directly connected around the perimeter by tape), and because it was reflecting some my body heat back to me, it was a bit noticeably warmer and had less condensation.

So, i really like the idea of a similar set up but with much stronger and more durable materials, a more windproof and stronger design, and using a couple of beeswax candles to help increase heat generation inside. Candles look really cool inside a shelter with a reflective liner!

I think the more traditional liner idea is a good one too, but will not utilize heat from my body and a couple of candles as efficiently as the above. Imagine a shelter wherein it tends to be 25 to 35 degrees warmer inside (i'm just guessing) than ambient air temps outside, and no need to chop wood, make a real fire, etc

Unfortunately, unlike a real hot tent with a wood stove, it will not have the side benefit of drying clothes and gear out, if anything things might become a bit more damp because of increased moisture. Hard to say, but i would like to at least try it out.

The basic concept seems a bit like the old Stephenson double walled, reflective inner tents, with a couple of candles added. However, i think the pyramidal like shape of a Mid, will tend to reflect IR back down more efficiently than some other tent shapes. Again, hard to say, but would like to test it out at least.