Why not eVent on bags anymore?

[Brett Peugh]

I know they did this a few years ago on some bags, but why doesn't anyone really use eVent for an outer shell? Or let alone on the inside to stop you from sweating into the down?

[Stephen M]

Feathered Friends used to offer Event on their bags but now offer some flavour of Wpb Pertex, Crux in the Uk still do.

I have a Crux Event Down Parka (11oz down) for wearing to work and casually in Michigan winters and love it.

[Matt Dirksen]

Don't know about the departure away from using Event (probably cost), but once a person is sweating inside a sleeping bag, no "vapor permeable" material will do any good any more, since you are now dealing with moisture, not vapor.

Sweating in a sleeping bag is a symptom of a larger issue.

[Jerry Adams]

eVent is sort of heavy, maybe 2 ounces/yd2

[Hamish McHamish]

For a while some quilts were available with a layer of eVent at the foot and the neck to better repel condensation at those commonly wetted points. I don't see this much anymore, so did it not work well, or at least not well enough to justify the cost?

[Stephen M]

I am wondering how well Neoshell would do as a sleeping bag shell?

[Nathan Watts]

You might want to consider using an eVent bivy instead. It will give you a little more flexibility for how/when you use your bag.

The extra expense of buying a separate bivy might be offset by having the ability to use it with bags of varying temperature rating.

Plus, it'll be 100% waterproof, unlike most bags made from WPB fabric.

[Dan @ Durston Gear]

There's really two moisture issues at play: moisture from the sleeper and external moisture (humidity, condensation, snowmelt etc).

Moisture from the sleeper can be a problem if it's either too humid or too cold to allow the moisture to pass through the bag and escape. Normally this isn't an issue, but for an extended trip is very wet or cold conditions it can be. It wet conditions you can hope for a dry period to air the bag, while in cold conditions its a bit tougher which is why some people use a true vapor barrier (non-breathable) to stop body moisture from entering the bag in the first place. A WPB membrane like eVent lets moisture though, so it doesn't really solve anything as a liner.

More commonly, WPB shell fabrics are/were used to protect the bag from external moisture like contacting condensation or dropping it in a river. The problem here is that using a WPB membrane to limit the entrance of external moisture ends up slowing the escape of moisture from the sleeper, so you reduce one kind of moisture and increase another – no real advantage unless you lack the skills to avoid sleeping in a puddle. GoLite (and others I'm sure) have taken a smarter approach to this by using WPB fabrics only at the ends where the bag is most vulnerable to contacting condensation and then using regular fabrics for the middle 90% of the sleeping bag so sleeper moisture has the best chance to escape. This can be a good design depending on your usage. It's unnecessary in dry areas and for users of robust double wall shelters, but it can be a good thing for tarp users or people using a small single wall tent that collects condensation.

Most people who hike quite a bit would agree that type 1 is the bigger (only?) concern of the two types, as avoiding external moisture just requires some basic skills and maybe a drybag while you hike. Since WPB fabrics do little for type 1 moisture, they don't really benefit sleeping bags.

[Daryl and Daryl]

Dan,

Thanks for the summary of the issues. Very helpful.

[Jerry Adams]

If it's really raining a bivy doesn't work very well, even though Ryan has demonstrated it's possible.

If you have a wet jacket you have to take it off and open up bivy, get in, close it up, find place to put wet jacket. If it's raining it'll get wet inside. And fabric directly on your face isn't good, better to suspend it above.

If it's just condensation from the humid atmosphere or a slight mist or brief drizzle, then bivy is more practical. In this case something like M50 is lighter and sufficiently water-proof.

My current bivy is eVent but I'm planning on switching to M50 to test this out.

[peter vacco]

i had a goretex bag, and it was muggy form the very first moment of use. now i have a WM dryloft bag, and it is a dream.
i also have a WM higlihgt, i think it's a highlight. blue, light, 28oz or so … and it is not dryloft.
this blue bag, in the same akto as the dryloft bag, in a good cold wind, you can feel some breezes thru.
it's not a huge thing, but it is noticable. just barely.

the dryloft completely eliminated the muggyness and slow drying of the goretex bag. i like that is may also give another layer of serenity if the tent blows apart.

[Javan Dempsey]

One thing I'll add to this, from my experience as a custom quilt maker, and user.

If you're cold, and sweating, you have inadequate bottom insulation. If you're hot and sweating, you need to vent your bag/quilt.

It's pretty much that simple. Of course, you may be hot and sweating from having an inappropriately warm bag for your conditions, but usually, people figure that out quicker than "I'm freezing but I'm sweating."

Many many of us here carry inadequate bottom insulation in pursuit of arbitrary base weight goals. Next time you're cold, or sweating on the trail, ask yourself where you're cold, and how you're cold, it may be informative.

[Derrick White]

As stated bottom insulation is key. It can take your top layers so much further.I have learned this from experience.

With good bottom insulation (Exped Downmat UL 7 for me) I can be comfortable through a wide range of temperatures in the same sleeping bag. I use my downmat all year round in temperatures from 25C to -25C.

On top I use either a WM ultralite bag (-5c to 10C) and a EE Revelation quilt for 0C and up. For really cold I use both the bag and the quilt (-15C to -5C, and that's pushing it), and when necesary (-15 and under) an MLD EventCuben bivy around the pad, bag and quilt.

Always in a 3 season tent. Always have more warmth than you think you need and vent as necessary.

The temperatures are estimates.

Ooops ….. I think we are off topic.

Derrick

[Tipi Walter]

I asked this same exact question here and never did get a real answer.

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=57524&skip_to_post=487855#487855

I suppose the best thing to do is call Feathered Friends and ask them exactly why they dumped their eVent bag shells.

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