Get ivory liquid dish soap (or equal) and mix it in water. Just as if you were blowing bubbles and smear it over the pad. If the leak has adequate pressure, it will start to make an air bubbles on the exterior at the leak location
I’m sorry guys should have been more descriptive. I’ve done soapy spray and fully submerging every inch and cannot find it. It’s definitely a slow leaker but I cannot for the life of me find the leak.
I bet its only deflating when you put weight on it after its blown up in that case its probably the valve. So fill it up again put it in tub and add your body weight. See if that makes it leak. We just replaced one that had a leaky seam where the material was glued together so we contacted Big Agnes and they sent us a new pad after we showed them that we had cut the corner off the current mat. THey wanted to make sure we where not trying to get a brand new extra mat.
I had a small inflatable pad for sitting on that kept going flat. I submerged it in the bathtub expecting to find a hole or two and an easy patch job. Stupid thing must've had a million tiny holes in it. Assuming it was of those small thorny vines that got it.
Had exactly the same problem with a 4 year old air mattress, slow leak which just couldn’t be detected. Kept waking up on hard ground with an empty air mattress. Started out trying to patch it while still out in the bush, submerged it in lakes, streams, etc. and still couldn’t see any bubbles. Once home did the same thing in the bathtub and sat watching endlessly but still couldn’t see any evidence.
Called Big Agnes to see if they had any thoughts, and as another poster pointed out, they asked for a pic of the valve cut off and promptly sent a brand new replacement.
Excellent customer service like that is very much appreciated and that’s why I’m taking a second to mention this. Thank you Big Agnes!
I had a similar situation with my thermarest xtherm. I even took it to a swimming pool with goggles and couldn’t find it. I think the problem is with the valve. I cranked it down last time and it held air.
I had same issue last year with my Nemo tensor. Couldn't find the leak to save my life. Sent it in for repair and they promptly patched it near a seam and sent it back. No fuss no muss. Great customer service for sure.