It turned out awesome and it was super quick and easy to do. Seriously, like 5 minutes tops! All you need is some Heat n Bond Iron on Adhesive. It's meant to be used on fabric (I use it all the time) so you can find it in most fabric stores like JoAnn's or even in the fabric aisle at Walmart.
Check out how it works on puzzles...
2. Put another piece of poster board (here I used two to cover our big puzzle) over your completed puzzle to make a puzzle sandwich ~ poster board, puzzle, poster board.
3. With your puzzle sandwiched in the middle, carefully flip over your pieces. Remove the top piece of posterboard and you'll now have the back of the puzzle facing up.
Now get out your iron and Heat n Bond...
4. Cut a piece of the adhesive paper about 1/2" larger than the size of your puzzle.
5. With the paper side up, use the medium heat (no steam) setting on your iron the paper onto the back of your puzzle. Go over it a few times to make sure it sticks to the back of each puzzle piece.
6. If your puzzle is large like mine was, repeat with another piece of the adhesive paper so the entire back of the puzzle is covered. (It's okay if it overlaps in places.) Go over the whole puzzle, making sure the paper is sticking all the way to the edges and to each piece.
7. Once it's adhered, you'll be able to easily lift your whole puzzle up. Flip it over and trim off the excess adhesive paper. I found that an exacto knife gave a much better and closer trim than scissors.
I originally thought I'd have to mount the puzzle onto a piece of foam board or something after I ironed on the adhesive, but it worked really well without it and I didn't think it was necessary. As you can see in the picture above, I'm holding the whole puzzle just by one corner. It was as stiff as a sturdy piece of cardboard and didn't flop around at all (unlike another puzzle we'd done before using the puzzle glue). All of the pieces were securely attached, but there was no brush strokes from any kind of glue to distort the image.
I just used two small nails to hang our puzzle on our playroom wall. ( I drove the nail through a spot in the corner where the puzzle pieces joined )
I think it looks awesome. It was super quick, not messy at all and it made our puzzle nice and sturdy. The adhesive comes in a large roll for just $10 or so. It's enough to do several puzzles (or puzzles and other fabric projects) ~ so it's way cheaper than buying frames to display your hard work.
Sharing our puzzle saving idea at: