What's wrong with my Thermarest and can I fix it??

[Moondog55]

used it again last week-end and the same thing happens.
I can blow it up hard and it will hold air almost forever but when I sleep on it the thing deflates and lets me contact the ground. I put it in the bath and I can detect no bubbles coming from the surface.


As I cannot afford to buy all new gear and my priorites keep changing I was wondering if this is a common problem and if there was a solution?? is it going to be a lost cause or can it be rescued to get me through just one more year??

[dee_legg]

Take it back to your place of purchase and have them send it to the supplier to be tested. I hope you kept your receipt.

[Maelgwn]

Sounds like some tiny holes that only leak under more pressure than you can blow it up with. Maybe try squeezing the forcing the air out a bit when in water looking for bubbles.

Had a similar problem with my POE mat, ended up getting credit for it under warranty.

[corvus]

Take it back to your place of purchase and have them send it to the supplier to be tested. I hope you kept your receipt.

I agree ,they come with a lifetime warranty so take it back.
corvus

[Moondog55]

Nope I lost the receipt and I wasn't aware that the warranty was lifetime.
I thought Thermarest was 3 years only

[Moondog55]

Nope I lost the receipt and I wasn't aware that the warranty was lifetime.
I thought Thermarest was 3 years only

[corvus]

Moondog55,
It may have changed on new models but both our Prolite 4 Reg pads have Lifetime Warranty printed on the labels along with individual registration numbers,hope this helps.
corvus

[dee_legg]

Depending on where you bought it, you might be able to prove your purchase through their computer records if they match your bank statements. Worth taking it in and seeing what they can do.

[Packo]

It sounds like it is only leaking when you have the extra weight of you body on it. To try and find out where it is leaking you can try this.

Get a spay bottle and fill it with water and a bit of dishwashing liquid. Get someone to lay down on the mat and start by spaying the soapy liquid around all the seams and valve. If the seam or valve is leaking you will see small bubbles forming where the air is passing through the soap. If you don't find a leak at the seam then start testing the other areas.

[Moondog55]

Well I bought it at Paddys in Little Bourke St Melbourne about 15 years ago.
It has been repaired a couple of times with patches but the patches are not leaking.
I can no longer read the serial #, I think I'll contact Sierra Designs and ask for an opinion before I go any further

[Moondog55]

Whoops I meant Cascade Designs

[andrewbish]

I had a similar problem with my similar-vintage Thermarest. I inflated it, then gradually moved sections of it unde water (in our laundry tub), while rolling/folding and squeezing from the other end to add pressure. I found the leak - seams were the culprit.

[JohnM]

15 years usage is pretty good for an inflatable product. Not suggesting that you don't try and take them up on their lifetime warranty, just making the point that it's obviously decent kit.

Yeah, at that age I'd definitely think it's the seams, more old-age than a traumatic puncture. I've had one of about similar age do the same, but it was a 3/4 length and I wanted to upgrade to full-length prolite, so I just got rid of it.

[Birdie Claws]

If the warranty claim doesn't work.Maybe you could try seam sealing the whole mat? Mix up a batch of silicon/meth and just lather it over the mat. Apply more over the seams.

[sailfish]

Agree that seams are a likely suspect. However most patching glues do not last well at all and in my experience are often a source of such problems as you describe. The better glues like Seamgrip, Stormshure and others take 24 hours or so but last decades. It can be difficult to locate very slow leaks like this but if you suspect old patches at all, it may be worth replacing them out of hand with one of the better glues that don't need a patch.

Ps. gluing the edges of existing patches never seems to help, pull them off and replace.

Regards,
Ken

[Moondog55]

I could not find aa mate who was willing to lay down in the bath for me.
I found a slab of marine ply and a foam offcut and used some weights from the barbells.
I think I found the problem and as Ken suggested it IS brittle hotmelt glue I believe. Anyway i just removed all the old glue and I have repatched with a chunk of packcloth and roofing silicon.
I'll let it cure for 24 hours and try it out.
It was such a tiny tiny trickle of air tho, and it only showed up after I had loaded the mat with 60kg of cast iron; another 22kg and the little trickle doubled, if I was still only 90kg I don't think I would have noticed so much

[Moondog55]

Well I did the patch replacement yesterday and all morning when I sit here posting i am sitting on it folded as I would out bush.
So far i cannot feel any sinking or deflating so it may see me though another wianter or two.
Thanx to every-one for the replies, and the advice to remove the patches and reglue was spot on.
Roofing silicon is more flexible than hot-melt so it should work much better

[rwfox]

Hi
If its one of the old brown mats they used to leak through the fabric just behind the valve. I have used Aquaseal® glue on ours. Just coat the fabric across the corner on both sides. I did ours at least ten years ago and they are still fine.

[Moondog55]

I can't actually remember the model name , but it is blue LOL Early onset "Old-timers disease" but 3/4 length and 40mm thick ( inch and a half) part of the problem seemed to be the actual patch fabric in the repair kit.
The hot melt glue looks like it removed the urethane coating from the patch and this allowed air to move through the nylon, I would advise anybody doing a repair to ignore anything but silicon.
As it has held up being sat on while folded I think it may well last another few seasons

[rwfox]

If you use Aquaseal you don't need a patch its so tough.
Its also good for repairing tents (not silone coated).
I have even ripped the tape of an old gortex and sealed the seems.
If you store the tube in the fridge it will last a while. Just put it in warm water before use, to get it to flow.