Finding an invisible leak in sleeping pad

Try folding the semi inflated mat in the bathtub and kneel on it. Sometime the leak only comes visible under a lot of pressure.

A rag with soapy water can do it too, but as Franco mentioned, the amount of pressure applied is important.

What Franko said.

And to state the obvious – you Are going to get wet.  It will be like a wrestling match.

Also, only partially inflate the matt so you can fold it into thirds. That way you can kneel on and closely examine each submerged section. A marker that works on wet fabric is essential.

Last, after finding and repairng the first puncture repeat the process just to be sure it was only one.

Have fun.

Also submerge the intake/outlet valve of the pad—as these things leak.  One time I was out with a big Thermarest and it had a slow leak but I had no creek nearby—so I submerged the air valve into my cook pot full of water and there it was.

Another time I had to bushwack thru some godawful briar thickets and the top edge of my stuff sacked Thermy got pinholed.  Slow leak.  That night I was camped next to Bald River and blew the thing up to bursting and put in the river and lo and behold found the leak.  Used McNett’s to seal it up.  Good to go.

My main interest in the OP’s post is this:  Do you remember in any way the pin hole was caused?  This is important for the Lessons Learned crowd.  I’m a stickler for keeping my inflatable pads from getting any kind of holes—so just wondering.

Speaking of inflatable leaks—it amazes me to see backpackers in our Southeast mountains hiking thru thickets with their Thermarests or other brands strapped directly on the outside of their packs—sure recipe for a slow leak.  And then they wonder why they’re on the ground after a couple hours.

Thanks for your suggestions! I will give it another go today.

@tipiwalter, I have no idea what caused the leak. My pad is always inside my pack if it’s not in my tent.

Some brands of pads seem more prone to leaks, Big Agnes AXL for one. T-rest valves sometimes. Pads with 20 denier fabric (Nemo Tensor, T-rest Uberlight). Weld spots can develop leaks (REI Flash). Quality control standards vary. Owner use is a factor but not the only factor.

Age is also a factor. I had a mattress develop slow leaks identifiable in the bath tub all over the place at an increasing rate. I eventually concluded the coating on the fabric was failing and retired it.

I had a pesky leak in my neoair once that was about to send me over the edge into nutland.  I finally sent it in for factory repair.  Therm-a-Rest send me a new one within a week. Check with the manufacturer of your pad.  They may have a repair service.

I found the leak! It is now patched and drying. It “only” took me another 30min in the bathroom wrestling with the damn thing to finally see bubbles. Thank you all! I hope there won’t be a next time, but if there is, I’ll remember the folding and kneeling on top trick.

For what it’s worth, this was a thermarest neoair xlite that’s about a year old and has been on less than 10 trips.