Question for Exped SynMat Owners

How did you blow it up when you did? Pump bag or by mouth?

KJ

by Mouth. I got it pretty firm to start with. The difference this morning is noticeable (is not flat though)

Your breath is warm and moist. As that air cools it loses volume (warm air takes up more space than cold). It's very, very noticeable when you blow up your mattress on a cold night.

Thanks Jennifer, that makes sense. I kept the mat indoors though so it was not cold (it was a test) but I'll do another test "topping off" mat a few times so the mix of air inside mat less warm (btw, I love the inflation/deflation system this mats have)

When I first had mine, I had a similiar problem. Then I realized that the valve flapper wasn't seating completely, allowing air to leak out. This never happens when I inflate it with the schnozzel, but occasionally does if I do it by mouth.

Even if you kept it indoors, the ambient temperature was probably much less than the temperature of your exhaled breaths.

Top it off with more air a couple times, then repeat the weight test.

Thank you all for your input. I do have an instaflator and I found a thread where Jack Elliot suggested a modification to the Instaflator so it works on the EXPED valves/mats (Basically chunk of 7/8″ O.D of Vinyl Tubing). So I will try that.

Meanwhile I have emailed Geartrade/Backcountry about this issue so they know there may be a problem with this pad. I really hope this works as I got a pretty good price and the pad seems very nice.

"I bought a used Exped SynMat UL7 from GearTrade"

Early versions had a problem with the interior coating that rendered them permeable. Mine would deflate significantly overnight, indoors, and I use a pump, but no amount of "bath tub time" revealed punctures or leaks.

If you can't find a leak after diligent searching, send it back to Exped. They will either find and repair the problem, and/or send you a serviceable matt.

I think the previous posters have hit the nail on the head in terms of why the pad might have deflated!

One thing that I would add: Shortly after getting my mat, I purchased an Exped Schnozzel pump bag, and I LOVE it for two main reasons. I've primary used this pad at high altitude, and it keeps me from getting lightheaded when blowing it up (I have a small, and it still seems to require a lot of air). Second, it keeps me from blowing my MOIST breath into the lofted microfiber. I have a friend who uses this same mat, and we've noticed little mold spots appearing on the inside of the mat recently.

Enjoy!

If the temperature at the time of inflation is several degrees higher than the night temperature , using a pump , it will deflate a bit.
The opposite is also true.
If you inflate it fully and then you expose the mat to the sun it will expand possibly causing those baffles to come apart…
Just last week fiddling with some mats I had my half inflated Neo Air self inflating to a hard structure after only about 15 minutes.
Mind you it was about 100f.

I noticed Exped has two valve designs. One which is flapper/hinge design and another which attached centrally via three spokes. The pad I own with the hinge design occasionally gives me issues like Gary mentioned above, even using a shnozzel bag everytime. Even if it turns out to be one of the other issues posted above, it's always good to check the valve.

If hinge gets stuck in the valve opening it can csuse issues.