How long can they be kept before they rust thru? I have heard of spray paint cans failing after several years and launching their contents into the room.
I just used some 18 year old cans of spray paint. Unused ones were fine, had to invert some used ones for a day or two to get them unclogged.
Depends on how they are storred. It gets damp here: my tools and spray cans gradually rust if left in the garage. They rust faster if left with their feet in water. I’m surprised at a “launch” though: mostly pressure cans just fiz at the bottom.