Pac Lite for a quilt

"I doubt much will breathe through the suit"

Are you referring to the down jacket and pants? There is no prior mention of a "suit" in your post. If you forgot to mention a VB suit that you plan to wear, I think a Pac Lite outer shell on a quilt is a fine idea, although its only purpose in that case would be to protect the down in the quilt from outside moisture, and you could do that for less weight and lower cost with silnylon.

If you will be wearing a down jacket and pants, I think an outer shell of Pac Light sounds like a bad idea. The breathability of Pac Lite is abysmal compared to something like eVent. It will do a good job of trapping moisture in the down, even under ideal conditions (warm temperatures).

It will do an even better job of trapping moisture in the down when temperatures are low. Pac Lite, like all Goretex products, can only move moisture out that has condensed, and is a liquid, on the inner surface of the membrane. If the air temperature in your shelter is 10F, the water that condenses on the inner side of the Pac Lite membrane will freeze there, and moisture transport through the membrane will be zero. Air-permeable membranes like eVent allow vapor to pass through, so moisture gets out (in limited amounts) even at sub-freezing temperatures. Even with a shell of very breathable uncoated nylon, though, moisture will condense and freeze in the outer layers of the quilt if temperatures are well below freezing. A vapor barrier liner or VB clothing are the only solutions I know of.

Josh,

My apologies but I am slightly confused, it the quilt for over your insulated clothing or for over a winter bag?

If you aren’t worried about breathability because to your VBL system, and chose PacLite for it’s weight, why didn’t you use cuben for the shell fabric? Enlightened equipment already makes what you’re looking for.

http://www.enlightenedequipment.com/product-category/epiphany/

colin- Sorry I wasnt clear I sometimes call it a suit but its the FF volant jacket and pants. And my thinking on the quilt is this. I did not get much condensation in any other area of the bivy just the top part of it where my breath was directly in contact with. How much vapor do you really think will pass through the down jacket and pants. I have attached a picture of the set up I have. Basically if people are getting vapor trapped in there "breathable" bags with out a down jacket and pants on(which is essentially the same materials as the down jacket and pants just cut different) wouldnt the same thing happen before it even gets to the quilt? I dont plan on getting any vapor barrier stuff. and I dont think gortex passes liquid as you stated water is a liquid and if gore tex passed liquid it would not be water proof.

stephen- Yes the quilt is for over the down clothing. Pics of said clothing are below.

Eric- Sorry I failed you too. I dont have a VBL set up. And I might be the only guy on here that does not really like cuben. Makes a lot of noise and feels like plastic. I mean I get that is lighter but for me especialy in winter when I plan on using this I want comfort.

But I do still have a myog tarp that is cuben nothing special just a simple rectangle with gromits and two loops for the poles to set up.

now that there are pics chime in again. and colin please explain to me or provide me with a link about research that supports your thoughts as to gore tex passing liquid through the membrane maybe I miss understood you or you know something I dont. but is was my inderstanding that it only passed gas(excuse me lol).

and here is the bag im going to have customized.

"That night I slept with the door open (10 was the low that night) I think if I would have left it shut. The fabric would have done its thing and I would have had less of a problem."

Speeping with the door closed would have increated the temperature inside and the higher temperature would have helped reduce condensation.

Josh there are two types of water proof breathable fabrics on the market. Event has small holes in it that are too small for water to go through but air and vapor. Fabrics like event have two breathability specs, CFM (air flow through the fabric), grams of water per square meter per unit of time.

The second type of WPB fabric on the market is moisture permeable but not air permeable. In these fabrics (including PacLite) water condenses on the inside surface of the membrane and soaks in. The membrane is like wood. As the membrane absorbs water some works it way to the outside surface of the membrane where it is allow to evaporate off. Paclite like most polyurethane based WPB fabrics do not have CFM rating since air doesn't flow through the membrane. They only have a grams per square meter per day rating which is typically less than event. One consequence of moisture permeable fabrics is that the often do not breath well if at all in very low humidity environments. humidity inside a Packlite rain jacket needs to get high before it will start to transport moisture through.

Colin is correst when he said"

"It will do an even better job of trapping moisture in the down when temperatures are low. Pac Lite, like all Goretex products, can only move moisture out that has condensed, and is a liquid, on the inner surface of the membrane. If the air temperature in your shelter is 10F, the water that condenses on the inner side of the Pac Lite membrane will freeze there, and moisture transport through the membrane will be zero."

Moisture from your skin will not get through a packlite quilt. It will only build up condense and then freeze.

If you want to protect your quilt from condensation drips from the roof of your hooped Bivy, Event is a much better choice. However it is overkill for your applications. Event has a water proof rating, or hydrostic head, is 25000mm. This means that the pressure generated by a columb of water 25000mm high will not get through the membrane. This is great for heavy rain but it does to some extent reduce the breathability (CFM). A water resistance fabric like Tyvek or Gore Dryloft (now discontinued) would be a better choise.

Like Event, Tyvek has small holes so air and vapor can pass through. However unlike Event, Tyvek 1443 has a hydrostatic head rating of only 800mm (about 30 inches). Drips from the top of your bivy will not get through it. Unfortunately I have not sen a CFM rating for Tyvek but I believe it is quite high. You can get Tyvek 1443 from amazon.com for $3.50 a yard. unfortunately I don't know if anyone has ever made a quilt from it.

Then how is air passing throught the gore tex in this video? If goretex only passes liquid that forms on the inside of the jacket there should be no bubbles right? I see one thing and and am being told another. Im not trying to argue I honestly was hoping to see some sort of data or something that shows moisture on the inside of a water proof jacket and then passing through to the outside. I guess I need to hop over to gores site and do some more research cause from what I see and when people call it water proof breathable I assume air passes through and water doesnt.

http://youtu.be/FSyRDzBenCc

how much vapor do you think will be able to pass through the down clothing to the quilt? I imagin it would be a pretty small percentage compared to not haveing it on.

It states below that the pores on goretex membrane are to small to pass water through but big enough to pass air and some vapor. It does not say any thing about water condensing on the inside of the membrane and then passing through once its a liquid nor does the gore site. Please where are you guys getting your info from.

Design

Gore-Tex materials are typically based on thermo-mechanically expanded polytetrafluoroethylene (PTFE) and other fluoropolymer products. They are used in a wide variety of applications such as high performance fabrics, medical implants, filter media, insulation for wires and cables, gaskets, and sealants. However, Gore-Tex fabric is best known for its use in protective, yet breathable, rainwear.

The simplest sort of rain wear is a two layer sandwich. The outer layer is typically nylon or polyester and provides strength. The inner one is polyurethane (abbreviated: PU), and provides water resistance, at the cost of breathability.

Early Gore-Tex fabric replaced the inner layer of PU with a thin, porous fluoropolymer membrane (Teflon) coating that is bonded to a fabric. This membrane had about 9 billion pores per square inch (around 1.4 billion pores per square centimeter). Each pore is approximately 1/20,000 the size of a water droplet, making it impenetrable to liquid water while still allowing the more autonomous water vapour molecules to pass through.

Effect of water repellent on a shell layer Gore-Tex jacket (Haglöfs Heli II).
Both wear and cleaning will reduce the performance of Gore-Tex clothes by wearing away the Durable Water Repellent (DWR) treatment on the surface of the fabric. The DWR prevents the face fabric from becoming wet and thus reducing breathability. However, the DWR is not responsible for the jacket being waterproof. This is a common misconception, so when the face fabric becomes soaked due to an absence of DWR, there is no breathability and the wearer's sweat will cause condensation to form inside the jacket. This may give the appearance that a jacket is leaking when it is not. The DWR can be reinvigorated by tumble drying the garment or ironing on a low setting.[9]

You can Google or YouTube the video for Stoic Vaporshell jacket membrane air permeability test. In it, they demonstrate that event/dry.q (can't remember which they test) and stoic vaporshell passes air through, but Gore-tex does not.

Thanks Andy I will Google that video when I get home and try to get to the bottom of this….. if what you guys are saying is right I have been confused for a long time and would like to be set straight.

As others have said, you will likely have condensation issues and in temps below 32* it will freeze on the warm side of your quilt. To allow the vapor to not condense against the PacLite fabric you will need to insulate the membrane layer from the cold. There have been a few discussions on BPL regarding a synthetic overquilt for such purposes. I feel that the PacLite fabric is unnecessary unless you are wearing a VBL.

no one has yet addressed the fact that I will be wearing a down jacket and pants and how much vapor will be trapped in that which should minimize the frozen condensation in the quilt.

BTW I had a Sleeping bag made out of eVent(Got stolen) and It worked really well. I only used it in winter and never had any issues with condensation in the insulation but I know it breathes better than gore.

Also this bag is going to be for winter only so weight for me is not a factor as it will be in a sled.

Then what do you guys think about Epic fabric. It is water resistant (I think its an encapsulated fiber) I used to have a FF hyperion jacket(stolen) that was made out of it. It didn't seem to be that water proof. But now that I think back I might be over estimation the need for a completely water proof fabric maybe I just need something that is more water resistant than Pertex Quantum .8 which is not water proof at all and the DWR is worthless. but the bag weighs nothing and in my summer set up I don't have to worry about getting it wet.

Josh,

A sleeping bag and down jacket got stolen, where you back packing in South Central LA?

Stephan
Lol No I Had a sled packed full of gear this year that got stolen after a trip they also took a split board, boots,camera lenses ect ect. The total for the insurance claim was about 7 grand. So in the last 3 months i have bought a whole new set up. hence the reason I am getting another winter bag. to warm to sleep in the gear above in my really cold bag so I want a new one. but I have to buy it a little at a time so my girl doesnt notice hahahha.

"It states below that the pores on goretex membrane are to small to pass water through but big enough to pass air and some vapor. It does not say any thing about water condensing on the inside of the membrane and then passing through once its a liquid nor does the gore site. Please where are you guys getting your info from."

There have been a number of different versions of Gor-tex fabric. The first verison was a layer of expanded PTFE applied to fabric. This version was very similar to Event and was air permiable. However body oil would get into the pores and plugging them up. This would make the jacket non breathable and apparently the oils could pull water through the membrane causing the fabric to leak.

Gor solved the oil issue by applying a very thin polyurethane layer to the inside surface of the PTFE membrane. This made the jacket vapor permiable but not air permiable. It also reduced the breathability but with no compitition at the time that was OK. Since then due to compition Gor has been trying to make the fabric lighter (packlight) and been trying to recover the breathability lost to the the polyurethane layer. Some of the most recent versions are now air permiable.

Event, like I mentioned earlier is very similar to the original Gor-Tex fabric. The only difference is the manufacture of Event found a way to prevent oils sticking and filling the pores of the PTFE membrane without resorting to the polyurethane layer Gor used.

Hi Josh,

Was is stolen out of your car?

I have used heavily insulated down clothing with a lighter sleeping bag in the past and got on well with them, one problem though is if the jacket or trousers gets wet or damaged it could cause issues.

Thanks for that little bit of history Steven and it does make sense that the tec would have changed a little over the years.

Stephan- it was in my garage but I think they saw it sitting in my car that's how they new it was in my garage that night. Usually I would have it in my house drying out. I don't use the pants and jacket during the day as they are way to warm for activity, so generally they are going to get same amount of use as a sleeping bag. I wear my Arctyrex SV bibs and jacket with a UL Patagonia down sweater or an rei prima loft jacket. I really like this set up just because I stay up later in stead of crashing at 7 cause I'm in my bag cause its cold. And peeing at night I usually pee at least once and peeing in a blizzard in base layers SUCKS! I have put it away before a proper shake more than once.

Hi Josh,

Sorry to hear that your gear got knocked over, at least the insurance paid out.

Normally I would not use my puffy jacket and trousers during the day unless stopped for more than 15 minutes or so.

I was really surprised I was able to push my Western Mountaineering Alpinelite (rated at 20f) to -13f by wearing Volant Pants and Gooses feet booties and Parka (it has 250g down) in the bag, the forecast was for about 10f so those temps where unexpected.

stephen- oh ok I did not know if you went to really cold climates and wore that while moving and thats why you where more worried about damaging ig and inturn your sleep system. yeah I was surprised at how warm the thing was also I was up that night my bag was getting damp just sitting on a rock enjoying the night. there was a big moon and I just watched the sun come up with a movie on my ipad not cold at all.

Thread update:
I decided to just go with the epic fabric it seems that the gore is going to be a bit over kill.