Instructables
Picture of How to Fix your Leaky Thermarest
I'd been using foam pads for backpacking for a long time, but last summer I bought a used Thermarest through Craigslist. What an improvement. But after I used it continuously for 3 months in the Drakensberg, the Outback, and the Fiordlands, it would only hold air long enough for me to fall asleep. It would slowly deflate and somewhere around 1am I'd finally settle down to the ground, get a rock in the hip and have wake up to reinflate the pad. No good. 

Got to patch dem leaks!
 
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Step 1: Find the holes

There are a couple ways to do this. I used my bathtub, which is probably fastest. Fill it with about 3 inches of water and then submerge sections of the pad until you find where the bubbles come up. Have a sharpie nearby so you can dab the pad dry and mark the hole. You can also sponge the pad with some soapy water to find the leaks.

Once you've marked all the leaks (mine had two), set it out in the sun to dry.

Step 2: Plug the Holes

I used some polyurethane epoxy to patch the holes because it has a bit of flexibility even after it is fully cured. I had some nice Double-Bubble pouches lying around. Regular epoxy would probably work just fine too as long as you don't coat too big of an area as the epoxy might pop off. If I were really clever, I'd find a way to fix this Thermarest in the backcountry. 

I opened the valve to deflate the Thermarest before applying the epoxy so that the air wouldn't blow a path through the curing epoxy.

Mix it up on a piece of cardboard pulled from the recycling bin and dab it over the place you marked with the sharpie.

Let it set for a few hours and then test out how well it holds air!

DonB24 months ago

Field repairs...I always carry some Shoe Goo and a square of ripstop nylon about 12"x12". I have repaired my backpack after a chipmunk chewed his way in, my tent (floor, roof, door, and fly), my sleeping bag AND my Thermarest (numerous times).

1.) Apply a thin layer of Shoe Goo to the hole, tear or rip and your patch that you have cut to be slightly oversized. I use a stick to rub it in and saturate the fabrics. 2.) Allow to flash over for a few minutes. 3.) Apply the patch and use that stick again to make sure there are no air pockets between the two. 4.) Allow to cure.

I should note that I usually apply a two-sided patch when on my tent. I ended up patching my backpack two-sided as well.

jsawyer1 year ago
McNett makes a Field Repair kit, which includes a small tube of Seam Grip glue.

Personally, I always carry a small tube of GOOP. They're available in miniature tubes if you buy the multi-pack. The only downside is trying to find/dry/repair while in the woods...
TeckyBecky1 year ago
You could try sugru. That would meet your back country fix needs.
danielhfourie (author)  TeckyBecky1 year ago
Possibly :)
I'd be worried that sugru wouldn't stick well enough though. I was thinking more along the lines of tree sap or resin ;)