I'm doing a science fair and I'd like to know if leaving glue in the open makes it stronger or weaker. I've tried super glue, white glue and a glue stick and I've obtained my results, I just need to back them up. I applied different weights to the glues after leaving them to dry for 1, 6 and 24 hours. Can anyone tell me what happens scientifically and some sources would be nice, but an explanation as well.