Nearly everyone has heard of expanding foam, or “expandy foam” as I call it. It’s the stuff that comes in a spray can at your local home improvement store. It has a long tube that screws on to the top, and when you squirt it out, it usually looks like a thick, solid yellowish foam that expands over time as it dries and hardens.
Generally speaking, most people use it for insulating gaps, sealing around newly-installed windows, sealing cracks or gaps in old roof structures, etc.
What you might not know is that it has another particularly handy use.