I was about to post a question if anyone ever used hot glue as an insulator. Glad I did a search first. I just spent most of the day putting together a fairly intricate circuit on a 1.5 x 1.5 perf board and thought about coating the bottom (solder) side with hot glue since this will be stacked with several other 1.5 boards. I just want to make sure something like a coin doesn't get dropped in there and starting shorting things. Did you ever have any issues with hot glue aside from the ones you mentioned? I know I will be SOL if I have to make a change so I will be testing very carefully.