Per this video
http://www.youtube.com/watch?v=kumSl-cbLlY
First step was to cut 12" off the foot end and trim back the innards to the first crease.
I then cut another crimped segment off the pad and pulled the innards out of that.
I plugged our iron in and set it at max and let it come up to heat.
First test was on the 2" wide piece to see how the xtherm material would react to that heat setting. The bond was effortless – a little too much so in fact so I took the iron setting down from 7 to 6 and waited 5 minutes.
Having cooled I subjected the 2" piece I'd bonded to a pull test and found that the plastic membrane of the top (silver) layer would in fact delaminate without the heat-bonded adhesive separating.
2nd test was on the 12" section that had made up the radiused foot end of the pad. I c-clamped it to the ironing board per the video.
Here's where I diverged in technique a bit from that shown in the video and for two reasons:
– The xtherm is made with a "sticky" exterior both top and bottom halves (I assume to resist slipping on tent floors and bedding) so the iron showed significant drag
– Even the '6' heat setting is enough to deform the plastic membranes slightly
Given these characteristics I knew I wouldn't be able to slide the hot iron sideways as shown in the video without introducing wrinkles – each with the potential for leaks.
My method then was to place the side of the iron against the clamped straight edge and pull outward, using my left or right hand to tension the material as needed to avoid wrinkles. I worked this way smoothly but rapidly from the middle outward toward each corner.
Note we are still experimenting on the 12" end piece here.
I sealed the cut end all but 1/2" in one corner and loosened the clamps and pulled it out from under the straight edge. I then blew air into the 1/2" opening to inflate this test piece into a pillow and rapidly plopped it down onto the ironing board and sealed up that last 1/2" and let it cool for 2 minutes.
I then place it onto a coffee table and sat on it to watch TV for a few minutes. My form would not be described as svelte so this was an adequate test.
All was well with that so I put the now 63" xtherm under the straight edge and clamped her down and had at it. Easy peasy. Anti climactic even given all the hand wringing in preparation to pull out the scissors and make that first cut.
One caution: do not apply too much heat or you will introduce small bubbles into your heated joint. Something is off-gassing or delaminating or whatever. Test on the other two pieces to find the right heat and travel speed for your iron.
You want the iron hot enough to deform the plastic slightly as that's how the factory joint looks. But too much and you'll get the small bubbles. Use your practice pieces to get the final joint right and you'll see how easy it is.
I'm going to save the small pillow segment I made for something. Maybe nothing. Might come in handy for the outdoor concerts my wife likes to go to.
