Well, I'm wondering if anyone has a solution possibly for a minor issue I've been having with my sleeping pad. I'm even curious if anyone else has has any similar issues.

My problem would be that when I get around to blowing up my sleeping pad, it eventually loses much of its air throughout the night. At first I thought it might be leaking air somewhere, so after this trip I returned from this past weekend I blew it up and let it sit all day. It was still inflated just fine.

So, knowing now that I don't have an obvious leak, I can only assume it loses air because the temperature goes from the 70's down into the 40-30 degree range as the night progresses. So while I start out with a comfortable cushion of air in the late evening, by morning it is probably half as full as it was.

While this really is only a minor inconvenience as far as I'm concerned, it is one of those things that bugs me merely because I can not currently see a way to prevent it at the moment. So I've come here to see if collective thought may provide a solution. I know I could go buy a new pad that doesn't recquire being inflated, but like I said, it is a minor inconvenience and more or less something that pokes at my brain to be solved.

Sorry but like trying to fight against gravity , you cannot defeat Boyle's law.
Of course it was much better when I was young and these kind of laws and regulations were not in place...
Franco
http://en.wikipedia.org/wiki/Boyle's_law

Franco: Are you trying to get us to believe that you tested the prototype "dirt"?

Matt: I agree with Franco. My pad does the same thing; always has. Your only option is to suck it up (groan!) and reinflate. Since I'm of a "maturity" that requires a 3am stroll to answer the call of nature, I just do it then.

FWIW, mine stays fairly full/tight all night. Maybe I just live a more virtuous life of something (good thing no one that knows me reads this stuff ...).

I've got a Montbell UL pad and toggle-to pillow, and used those a great deal on the trail last year, never felt the need to reinflate. It's a pretty thin inflatable, and I fill it pretty full/tight too.

Sorry - didn't mean to imply that mine went flat. It just deflates slightly; if it was very firm when I went to bed, it's just slightly firm by 3am. Were I lucky enough to sleep through the night, it wouldn't ever deflate enough to wake me up. (Mine's a Thermarest Prolite 4 short - which works, because so am I.)

It appears you do have a small leak. Inflate your mat/pad. Let a 40lb weight sit on it overnight. I use a 5 gal bucket of water. If there’s a small leak, the weight will be touching bottom in the morning.

To go from 75F (297K) to 35F (275K) is only a 7.4% drop in pressure. This is hard for a human to notice unless you are the princess and the pea. And it might be a less drop since your warm body is lying on the mat.

Pin-hole leaks are so hard to find, even under water, because you get micro bubbles that are hard to see. I had a thermarest with a pinhole leak that I couldn’t find. I sent it in. Cascade Designs found it and patched it. Actually they found two! So I won’t strap my thermarest to the outside of my backpack anymore.

-Barry

I am with Barry, I think you have a pinhole leak. They won't be noticed unless there is weight on the pad.

I agree, you have a pinhole leak - or a slow leak at your valve (I've seen that fairly often too..

put a weight on it.

Welp, I put weight on it to see if maybe there is a pinhole leak or the valve is leaking. The weight sat for about 8 hours or so. When I took the weights off and went to blow air into to see if it had lost any air, I couldn't blow any air into because it was still full. So I can only now rule out a pinhole leak or leaky valve.

I have had to make a change slightly to my initial temperatures though. Instead of a high of around 70 degrees, it has to be more along the lines of the 90 degree range roughly since the air is coming out of a body that is more than 98 degrees warm. This may be one of those things I'm going to have to wait until winter to confirm since it isn't cold at night here and I can only get those temperatures while hiking.

I'm thinking maybe I'll try blowing it up again though, adding a bit more weight and leaving it for longer since the weight that was on there today was not comparable to my own weight, despite being on there longer than I'd sleep on it. We'll see how it turns out here in a few days I guess.

As a teenager nobody in my village had the money to buy tents and I was not aware that there was such a thing as a "mat" so we slept cowboy style only one night at a time, in the middle of summer, a few times a year when we took our chances with the weather. That was at around 8000', home was at 3600'. We had sleeping bags made from animal hair....
Now a 1" mat is far to thin for me.
Franco

Welp, I put about 100lbs spread over the pad for around 12 hours and I didn't lose any air. That therefore rules out the pinhole idea, which means I'll pretty much just have to roll with a slightly flatter pad in the early cold mornings. I can't complain to much at the end of the day of course. It is far better than sleeping plainly on the ground like I used to have to do, lol.

Boyle's Law is persactly why I ret'd my Neo Air to REI - that and the bounciness of it. FElt like an inflatable doll - not that I would know about those things.

NEWS FLASH! I got lucky! At a Sierra Club Outings leadership course near Donner Lake in California a few weeks ago there was an end-of-training raffle for some outdoors equipment. I got The Grand Prize:
1. Trail pro Regular matress
2. fitted top sheet
3. snap-on quilted blanket
4. pillow

(Even a blind squirrel gets a few acorns.)
Eric

Do you inflate completely with your mouth, or do you let it inflate with ambient air and then top up by blowing in it. With
thermarests this works better because you end up with predominantly colder denser air in there and only a little bit of warm air from your mouth..

Alternatively be sure to inflate first thing when you get into camp and top it up later. before going to bed.

I actually can't think if I let it sit or not before I blow it up when camp is set up. Either way though I do blow in it again before I actually lay on it for the night.

Funny

Not everything expands when it gets warmer nor contracts when it gets cooler and the air in your pad isn't at ambient anyway cause yer layin on it. Sure Boyles law applies to the air, but not to the container. My Warmlight down air-mattress gets harder during the night and often I have to let some air out to soften it a bit. Since its 3 " fully inflated, it can lose some air and not suffer. I have to be careful not to over inflate it.
Jim
Jim