Cascade Designs patented the self-inflating mattress idea in the 1970s, and lots of campers gladly traded in their closed-cell foam pads for the greater comfort of a Therm-A-Rest pad. The downside is that the Therm-A-Rest pad, like any air mattress, is vulnerable to punctures. A pinhole leak will leave the sleeper on the cold hard ground. The ToughSkin pad from Therm-A-Rest adds a bit of closed-cell foam inside a Therm-A-Rest pad to provide a measure of puncture resistance. The fabric on the bottom of the pad is fused to a sheet of -inch closed-cell foam, which is in turn fused to the usual layer of open-cell foam. If a thorn, sharp twig or rock shard punctures the bottom fabric but doesn’t completely penetrate the closed cell foam, the airtight integrity of the pad won’t be compromised.
We tested the pad by pushing a safety pin at a shallow angle through the fabric, into the foam and back out the fabric again. After making several holes this way, we submerged the inflated pad, checked for leaks and holes, and squeezed the pad. There were no bubbles coming from the holes even when we squeezed the pad hard to create some pressure. We also set the pad on the floor, piled some weights on top of it and left it there. After two days, the pad was still fully inflated.
If you do happen to get a puncture through the foam and the pad leaks, at least you’ll have the closed-cell foam to provide some measure of insulation, perhaps enough to get you through the night. Repairs to the ToughSkin pad are the same as they are with other Therm-A-Rest pads, using the repair kit available separately from the manufacturer. The addition of the closed-cell foam adds only a bit more bulk. In the small size, the pad rolls up to a diameter of 4 _ inches—an inch more than the standard pad of the same length.