Help me! - understand cold weather condensation

[snull]

I haven't tried the panda without a pad yet but with the blue wal mart pad in the pocket i have been dry so far

[snull]

k... last night my thermarest pillow which was outside the panda's sleeping bag was quite wet, must have hit the dew point? makes me wonder if I leave it outside if that condensation will freeze, typically I leave it outside and put the pillow inside the bag but it was so wet i left it out...

[kohburn]

k... last night my thermarest pillow which was outside the panda's sleeping bag was quite wet, must have hit the condensation temp

makes me wonder if I leave it outside if that condensation will freeze, typically I leave it outside and put the pillow inside the bag but it was so wet i left it out...

outside the sleeping bag.. but was it under your head? under a tarp? out in the open?

[snull]

the panda is basically a sleeping bag that is stitched into a hammock... the head isn't sewn into the hammock all the way up so the pillow fits under the sleeping bag and on top of the hammock, i had a tarp, it never rained

side note the dew point was 26 degrees F and it got down to 24 degrees

I prefer the pillow outside the bag to leave me more room but I can fit it inside if I have to, that might solve it...

I think the bag has a 5000mm water colum so its pretty water/wind resistant, inside the bag was dry, it just felt like the pillow was a warm damp sponge on the top side only...

I wasn't sweaty, everything else was dry

so to answer your questions, I'm in the hammock, under a tarp, pillow is under my head (my head is inside the sleeping bag)

[slowhike]

the only thing i can figure is that even though you weren't sweating so to speak, some of the water vapor that is always being put off by the body collected on your pillow surface.
i believe they call it insensible perspiration, or something like that.

[kohburn]

so to answer your questions, I'm in the hammock, under a tarp, pillow is under my head (my head is inside the sleeping bag)

gotcha, now i have a better mental image of how it was all layed out.

i'm going to say that it was a vapor built up due to the insulation and sleeping bag attributes.. if it was inside the bag the vapor may have never condensed, or it may have condensed inside the bag hood instead of the pillow.

[Rapt]

Thermarests are totally air and vapour tight. They don't breathe so putting it outside the bag is like putting it on the cold side. It just gives a place for the vapour given off by the bag to collect and then cool and condense. Inside the bag it'd be more likely to stay dry because its on the WARM side of the insulation. It'll only condense there if there is an excess of moisture.

Think of your house. The walls are non breathable (in fact they have a plastic vapour barrier to ensure this) but they stay dry unless you do something like have a really long steamy shower. Then the excess moisture condenses. The whole point of that barrier in the wall is to keep the moisture in the house from condensing INSIDE the wall or insulation at the cold side and getting you insulation all wet.

[kohburn]

Thermarests are totally air and vapour tight.

i couldn't find anything on thermarest site to indicate that the pillows were anything more then a highly compressible camp pillow.

[snull]

k, tried the pillow inside the bag last night and everything stayed dry that time

[turk]

Okay, Snull , Rapt .... somebody ... help me out.

I spent another 2 nights in the Panda hammock. I used the panda hammock with a 3/8 " CCF pad in the pad pocket, and 2 centre-zip sleeping bags inside the panda bag. Looking something like this, if you picture the layers stacked from top to bottom it looks like this:

JRB 8x8 tarp pitched as diamond. Corners to ground.
4" air space between tarp and hammock
Upper DWR+insulation of panda bag/hammmock
down bag with DWR shell
Synthetic bag
Bottom DWR+insulation of panda bag/hammock
3/8" CCF pad
pad pocket sleeve DWR

temperature outside was 12.2 deg f with 20 mph wind gusts.
(-11C and 33km/h wind for my fellow canucks)

I slept snug as a bug, and made sure to keep my face out of the bags. No cold spots. I rubbed myself down with a tissue when I awoke to see if I could discover any body sweat. Barely enough to make a face tissue damp. And yet .... another 2 consecutive nights... still the same problem with the panda hammock bottom layer. It is just soaked.

I was trying this time to use the DWR shell of the first inner-bag to protect me from the soaking wet tafetta of the bottom layer of the panda bag. it worked, sort-of. But I am very concerned as to what will happen with this system if you drop the temperature
another 40-50 degrees.
I am not currently using any VB system. But I think I had better get a very serious crash course. The panda bag is soaked in a rough print of my body. You can even see the 2 circles that represent the balls of my heels. My down bag repelled some moisture penetration, but registers heavier on my scale by almost 1.1oz after only 2 nights. no other layers are producing any concern.
In the 5 minutes it took me to take down my sleep system and stow it. The moisture in the panda hammock had frozen. What do I do?

I am right out of ideas. This is the warmest system for its weight I have experimented and tested with. I really want it to work.
But I need an engineer to tell me what is wrong. If I need a VB layer, or if the pad and pad pocket are acting as a VB layer, and is causing a problem... where do I go from here? Nothing I have read on VB's seems to explain precisely why I am having a problem with this one particular layer of my setup. I am not sure what to do differently at this point. I am prepared to sleep in a goretex bivy sack against my sleepwear based on rapt's theories/experimentation on using goretex in a warm zone. But if that fails, I am completely out of ideas. At this point, I am willing to try anything.

Your thoughts and advice much appreciated. Snull... how are you not reporting these same issues? What are you doing differently?