The mounting strategy for these puzzles involves no puzzle glue, follows the steps from attempt 4 and attempt 4 part 2, using 3M 568 Positionable Mounting Adhesive. This is double-sided dry adhesive which is an alternative to Con-Tact paper and spray adhesive. The bond is positionable until firm pressure is applied, then the bond becomes permanent. For Monument Valley, since this one is a panorama, I wanted to mount it in two sections, much like I did with Underwater.
Read about additional mounting projects here including mounting large puzzles in detachable sections.
Monument ValleyI measured and cut the foam board for each half. Partway through I decided to put notches on one side so that the gap between the two sides would be smaller. In hindsight I should have done this on both sides, but it isn't a big deal since you can't tell straight-on. Here you can see the gap between the two halves, left so that they can be separated.
As you peel the backing sheet off, all of the adhesive is transferred to the puzzle. The backing paper will have no adhesive left on it and will feel a bit like wax paper. If this is not the case, lay the backing paper back down in that area and apply pressure until the adhesive transfers. This puzzle is rather loose, but the pieces did not move at all when pulling the backing off.
Here you can see the adhesive applied to both halves with the gap in the middle.
I lined the foam board up lightly and then pressed it down onto each half. Here you can also see that I've wrapped the edges with white duct tape to give them a smoother look.
I used another piece of foam board underneath to help flip the puzzle over, since at this point firm pressure hasn't been applied yet. Included with the adhesive is a protective sheet much like wax paper but thicker. This is used on the front to protect the puzzle while using the squeegee to apply firm pressure.
Since each half is mounted onto separate pieces of foam board, I'm able to separate them for easier handling once we move. This technique will be useful for very large puzzles. It's very important to still keep the entire puzzle connected when using this technique so that the pieces stay properly aligned.
I measured and cut the foam board and then wrapped the edges with black duct tape.
Laying down the adhesive:
Close-up of peeling back the backing paper:
Adhesive applied to the whole puzzle:
Update: When doing this one I accidentally put the foam board down on top a little too misaligned. I muttered some four letter words to myself and then, because I hadn't applied pressure yet, to my amazement I was able to very carefully peel the foam board back off of the puzzle and properly align it. Awesome!