My pressure canner is the self-venting type. Why do other instructions say to vent all pressure canners for 10 minutes?
All pressure canners, including “self-venting” Pressure canners, do need to be vented for 10 minutes before the pressure is allowed to rise. This venting time is a way to be certain that all air is removed from the pressure canner. Research has shown that under some conditions (particularly with raw-packed foods) all air may not be removed from self-venting pressure canners. If there is air in the pressure canner, the temperature is much lower than if the canner contains only water and steam.
