I found(*) a new technique recently that works everytime. Tap the edge of the lid on a hard surface while pointing the jar 45 deg downward. Tapping the lid is

I found(*) a new technique recently that works everytime. Tap the edge of the lid on a hard surface while pointing the jar 45 deg downward. Tapping the lid is a common suggestion, but the magic ingredient is the downward angle. * by found I mean shown, by a senior professor of mechanical engineering.