This is my preferred puzzle glue. Not only is the plastic 'sponge' applicator great for spreading but the glue goes on and spreads clearly and results in a nice Bristol board like puzzle sheet after which preserves the image nicely. I love being able to preserve my puzzles after I do them (since I don't really enjoy redoing puzzles) and have since been looking for more aesthetic puzzles to display because of how great the final result of using this glue is. Depending on how good of a job you did the first time, you shouldn't have any problems with pieces coming loose however the edges are hard to get right so you may have to reapply - this is a flaw with gluing things in general, not with the glue itself, so keep that in mind and take care when spreading to the edges. I can use one of these bottles for about three 1000 piece puzzles, front and back. I highly recommend this product if you want to keep your puzzles when you're done with them.