horizon wrote: ↑28 May 2021, 1:25am
Just to emphasise what
willem has said - we're not talking about puncturing, we're talking about internal delamination. This is where the sidewalls between the baffles become unstuck and combine to form large balloons, making the mat (although full of air) unusable.
The problem is worse because it seems to be unpredictable: it could happen in the middle of the night in the middle of a tour; it could happen with an old mat or quite a new one. And it happens suddenly. If they just got old and wore out, that would be fine. The system seems to rely on replacement under warranty. So it's a wonderful product that you basically cannot use (even though many people do and successfully).
In insulated air beds, like the Exped Down/Synmats, or the Thermarest Neoair, it is indeed failure of the baffles that form the visible tubes, so that instead of a set of narrow tubes forming a flat sleeping surface, you've got a big fat section.
With self-inflating mats, it's the shell becoming detached from the foam core (delaminating), again giving a big bubble.
Both have much the same end result - you don't have a flat mat any more, air goes into the bubble allowing you down onto the ground, and any attempt at adding extra air to compensate merely results in the bubble getting bigger. There's nothing you can do about it other than get a replacement.
By way of prevention, it would be best to avoid leaving a fully inflated mat in the tent during the day, partucularly if it's sunny. With a self infalting mat, you can just leave the valve open, with an air bed it means letting a fair bit of air out, and reinflating in the evening.
In terms of what's likely to fail, comparing the results of googling "neoair baffle fail" with "downmat baffle fail" is instructive. The Thermarest Evolite mats don't get a very good press either.