Pepper spray can be an excellent self defense tool and most people can easily learn how to use it effectively. However, a pepper spray canister does not last forever. Although the pepper ingredient (oleoresin capsicum or OC) does not lose its effectiveness (ask me how I know)—the propellant can and does lose its ability to spray properly over time.
You might have been wondering about the picture of piggies. Last year we had some wild pig visitations and they apparently found the grubs in my front yard particularly appealing. If you have never had piggies paying attention to your lawn, they can and will destroy it and can do so in a remarkably short period of time. A lawn that piggies have attacked looks like a drunken farmer plowed it in the dark.
As I was attempting to devise a way to discourage their interest, I decided to spray OC from expired pepper spray canisters on the yard. Spoiler alert: OC did not appear to bother piggies in the slightest, so this is not a way to discourage their interest in a lawn. During this process, all the expired pepper spray canisters did expel their contents in some manner; however, some simply dribbled the contents on my hand rather than spraying. There was no external indication showing which expired canister would spray and which was going to dribble. I did notice that the smaller canisters tended to dribble more than the larger ones. This is perhaps due to the lower percentage of propellant in the smaller canisters.
Replace expired pepper spray canisters and properly dispose of the expired canisters. This may mean throwing away canisters that are not empty, but this is a small cost in the broader scheme of things. Since the ability to maintain distance is a key advantage of pepper spray, do not rely on expired canisters for protection—you may get a dribble instead of a spray which will compound rather than solve your problem.
