Have you wrestled with trying to open a stubborn jar?
You know how it sometimes refuses to budge as you struggle and strain to twist that cap off. Have you ever busted a jar while trying to do this? There is no need for all the fuss and bother and there is no need to bang on the edge of the lid with a knife handle or the edge of a countertop.
Just use the same rubber gloves that you use when washing your dishes.
The gloves give you a firm grip on the jar and make twisting the lid off a heck of a lot easier.