Thermarest prolite apex fail.

[in4]

I heard a slight bang! last night whilst sleeping on my Therm-a-Rest

https://www.thermarest.com/ie/sleeping-pads/fast-and-light/prolite-apex-sleeping-pad/prolite-apex.html

I initially thought I had punctured the pad but on close inspection it appears the pad outer has separated from the inner and created a ‘bubble’

The bubble is at the head of the pad so I have an inbuilt pillow now. Thermarest are usually good re replacing faulty product so I hope to arrange an exchange in a few days time, when I’m near a branch of the supplying store.

It puzzles me why the pad chose to fail when it did. I’m only 80kgs and had inflated using 18 breaths as per the store’s advice.

Such is life on tour!

[mickeg]

Once the first separator between tubes pops, additional ones come fast after that.  It looks like yours has about 4 to 6 that have separated.

I have seen plenty of cases of that from various brands where failures were returned to stores.  Good luck getting that returned.

I am in USA, I have mostly used REI brand air mattresses because they had such good warranty coverage, until they didn't.  Now, everything they sell is capped at one year, and that includes the stuff that was sold with a lifetime guarantee.

My REI Flash mattress had a problem like yours this past April, once the first one separated, within a few nights, most of the mattress had separated and it was like trying to sleep on a beach ball.  In my case, they run lengthwise, not side to side like yours, so it only took a few to separate to make mine a disaster.  See photo. 

I have two other old REI mattresses like that, I am suddenly careful to keep them slightly underinflated.  I did a two week backpacking (not biking) trip, came home a few weeks ago, every night when I blew it up, I was not sure if I had a safe amount of air in it, I did not want it over pressurized. 

I am now putting just enough air in it so that if I sit on it with only my butt on the pad, my butt is on the ground, but if any more of me is supported on it, then it is supported by air because my weight is spread over a larger area.  In the past, if I sat on it, part of my butt would have been supported by air and not on the ground, thus higher pressure.  I hope my change of operation makes my others last longer.

I wish you luck in getting it replaced under warranty.

[PH]

I've had three go like that, a Big Agness and two Exped (The second being a warranty replacement for the first.)  I used to work in a completely different industry using the same HF welding technique on PVC, if you have a seam that isn't terminated in some way it's always going to be vulnerable to delamination, that is the PVC coating coming away from the canvas backing - Note how Ortlieb panniers have stitched edging.
Thermarest did try and minimise this by using shorter seams across the mat rather than the length.  Better, but as you've found out, not perfect.
There is a newer design, adopted by several manufacturers, which has a cell or button structure instead of tubes. I can't figure out the manufacturing process, but it seems to be robust.  Some manufacturers have such confidence in it they're offering lifetime warranties.  I have a Sea to Summit mat with just such a warranty, it hasn't yet had enough use to test longevity, though it's at least as comfortable as the others to sleep on.
https://seatosummit.co.uk/collections/air-sprung-cell-sleeping-mats

[John Saxby]

From mickeg:

I am now putting just enough air in it so that if I sit on it with only my butt on the pad, my butt is on the ground

I do something similar, George, with my Neo Air (now in its eighth season), and so far, everything continues to work well.

The radical reduction of warranties seems to be going across all sectors of the economy. 'Twould be easier if producers had a fit of candour and simply stamped their products "Let the buyer beware"...

[WorldTourer]

Delamination of a Therm-a-Rest pad like that is much more likely if you use your breath to inflate the mattress. That is why Therm-a-Rests today come with a pump sack that you are supposed to use instead of breathing into the mat. I think that Therm-a-Rest has a good replacement policy for delamination even if it was the user’s own fault, but I wouldn’t count on their kindness long-term.

[mickeg]

...
The radical reduction of warranties seems to be going across all sectors of the economy. 'Twould be easier if producers had a fit of candour and simply stamped their products "Let the buyer beware"...

Yes.  Fortunately, our REI still exists.  I only had one opportunity to shop at MEC before they went under.

[PH]

Delamination of a Therm-a-Rest pad like that is much more likely if you use your breath to inflate the mattress. That is why Therm-a-Rests today come with a pump sack that you are supposed to use instead of breathing into the mat.

No it isn't. I made products with that welding (Marquees, big tops, tilts, tarpaulins...) that spent their life exposed to the elements and the seams are unaffected by moisture. The reason not to inflate a mat by mouth is because the moisture isn't good for the insulation.

You can get an idea of the issues from the brief description in this link, under "Joining of technical textiles with stringent seam demands" though for a more thorough understanding you'll need to buy the book.
https://www.sciencedirect.com/topics/engineering/high-frequency-welding

[mickeg]

The comment on blowing it up with your breath reminded me that after a trip I like to inflate it a few times with air from a plastic bag to try to remove some of the moisture in the air mattress.  I have seen some spots on one of my air mattresses that I used on a tour that I suspected were mildew.  The fabric was not transparent, but was translucent enough that a mildew spot on the inside might have been visible.

So, thanks for the reminder, got home a week ago and forgot to purge any built up moisture from the air mattress, did that last night.

[in4]

I had a very positive outcome from the supplying store. Apparently my experience was new to them.
Additionally they recommended inflating the pad quite lightly; so as there is some ‘give’ in it.
Thanks for all the comments and insights. They are appreciated and add to the sum total of our collective knowledge bank.
No AI was involved in this post.

[PH]

Good result.  How long had you had the original? 

Additionally they recommended inflating the pad quite lightly; so as there is some ‘give’ in it.

Yes, Big Agnes used to recommend something similar to what mickeg mentioned, though their measure was you should feel the ground if you kneel on it. I've also heard it recommended that in hot weather, let some air out if you're leaving it in the tent all day.
Hope the new one lasts you well.