Tensor Insulated Sleeping Pad

What were the humidity levels when you camped? If you pumped a bunch of humid air into the pad, it seems reasonable at those temps that the moisture would fall out of air and condense both inside the pad and on the cold side of the pad touching the ground cloth. It looks like a lot but is probably not as big a deal as it looks. Keep it open when you get home and let it dry out so it doesn’t get moldy. Did it keep you warm enough? You mentioned it was comfy.

Just a link to understand how much water can be suspended in air for a given temp.

https://www.engineeringtoolbox.com/amp/maximum-moisture-content-air-d_1403.html

Thanks for the comment.

Not sure about the humidity level, but to be honest I’ve been camping for 10 years now in so many diffferent weather conditions and I should have experienced that some other times.I’m just feeling it has something to do with this pad in particular.

i’m now leaving it open to dry out at home as you say, but the think is waking up every morning and finding out you have wet conditions inside your tent is very bad as the ground sheet is becomes wet too, a nightmare, especially in cold conditions; not to say the pad will never dry on time and it will have to be packed still wet.

What i am try to say is that something very unusual; i’m thinking if it’s something that has to do also with this ultralight fabric they now use for the pad, like 20 denier. My previous pads were 50 denier. And  i want to see if anybody has ever experienced the same with other ultralight pads, for example thermarest neoair, or sea to summit.

The pad kept me warm most of the night, but early in the morning i started to feel cold on my back, not sure if linked with the condensation building up during the night. The R value of the pad is 3.3, so it definetly cover subzero temperatures.

i can tell you I’ve not experienced that with my BA AXL, and it is as light as it comes.

Thanks :)

It occurred to me that the design might present a problem in exactly that way, as far as condensation outside. I think that the additional air spaces allowed by the gridded design would also allow more air (usually somewhat warmed and humid) in the tent to seep under you allowing somewhat more condensation. This is likely part of the problem.

But generally, I think this has more to do with insulation and porosity of the tent floor (or ground cloth.) In many cases, water molecules dissolved in air are very penetrating, especially through things you would not associate with “leaking.” For example, some plastic films will hold water easily and not leak. But, they will pass water vapor through them after the molecule is disassociated in a media (air humidity.) Soo, a lot of the moisture you see might be from the ground sheet. I believe an old study done in the 60-70’s of water tubs used in Civil Defense shelters showed some to be less than half full and others were fine. Further study showed some were sealed when completely full, these were fine, but the ones that had a small bit of air in the seal were all low…through evaporation right through the plastic bag.

I have used tents in bad locations where I got flooded out during the night. I did not see any moisture inside (under a NeoAir.) Something with a head of around 10,000mm, like Exped used to use in their old tents. I have used tents with floors rated at 3,000mm HH and have gotten EVERYTHING touching the floor damp under similar conditions. (After applying two coats of silicone/mineral spirits…nothing, fully corrected.) So, a lot will depend on what your floor is and what is the coating used.

Often this is an indication that the floor is going bad. I have had several urethane coated floors fail after 4-5 years.

yeah, must be that the floor is letting water pass through it

if a fair amount of water dripped down and seeped under the pad that might be the problem

to explain the water under the mat

inside the mat? – you must have inflated it with humid, warm air which is contradicted by the fact you used pump sack, weird…

the inside of mat won’t dry out just letting it sit there.  Maybe inflate it, let it sit for a while, then deflate, repeat

The tent is 4 year old; to be honest the floor was last thing I was thinking about as it quite sturdy and hardwearing, and never gave me any problems like that in the past. But your very detailed explanation opened up my eyes about something I didn’t knowm much, thank you.

I wonder how all those ultralight tents (Big agnes, msr, tarptent, zpacks,etc) with very thin groundsheet manage to avoid this problem then, when they barely reaach 3000mm HH; probably they are all siliconed? never happend anything like that with my stratospire for example, though never used this nemo pad in it, always a thermarest, with flat surfaces, no baffle.

The condensation inside the pad is very weird though as i used the pump sack, i wonder if there is something wrong with this mat itself

Do you have pics of your campsite where you experienced this?

here a pic.

Lots of wet grass. I am not surprised you got water to soak thru the bottom.

The condensation inside the pad is very weird though as i used the pump sack, i wonder if there is something wrong with this mat itself
There should not be IF you dry out the inside.
As to where the water came from – I suspect that the air you pumped in was both warm and very humid. Then you cooled the mat right down.

No, if the mat holds air pressure it will NOT leak.

Cheers

as far is my experience that was a very good camping pitch. The grass is very short, I only had one night of rain, and it wasn’t kind flooding. Grass was most of time dry, apart at night when condensation built up outside, but hey that’s totally normal. The only reason could be a faulty groundsheet, but still not sure about it. We’ll hve to do a couple more nights out and see if it repeats.

My experience, with a variety of inflatable pads, is that condensation forms on the inside even if you use a pumpsack with zero use of your breath. The air can hold some moisture, depending on the air temp. So, one inflates their pad (using a pumpsack) with this air. But later, at night, the air cools, including the air inside the pad. This causes the moisture that the warmer (daytime) air held to condense into water droplets because the air inside the pad is no longer warm enough to have said water be in the form of vapor. So ya get water droplets in your pad. Yes, it happens to us all the time here in WA state (USA). This happens with Exped and thermarest (the only pads we’ve ever used).

We always inflate our air pads, when we get home from a trip, using a pumpsack, with no breath used (i.e., we don’t breath or blow into the pump sacks to fill it with air). We let the mat sit for a while (as few hours). The droplets inside evaporate (turn to water vapor). Then, we deflate the pad, blow it up again. We do this for 2-3 cycles. All this is done inside, in a heated room (68-70dgrees F).

Remember that if you fill your pump sack by blowing into it/using your breath, it’s probably nearly the same (in terms of moisture) as blowing directly into your pad with your mouth.

thank you so much