Although the process of canning has been around for quite some time now, there are still some commonly made mistakes that should be avoided whenever possible for your safety and the safety of your friends and family.
1. Not cooling jars in the canner - Rapid temperature change causes pressure buildup in jars and can result in fluid overflowing through jar seals and potentially causing the jars not to seal correctly. Take the lid off of the canner and let jars sit and cool for at least 5 minutes before removing.
2. Not venting your Pressure Canner - Vent canner and allow temperature to build. Allow to steam solidly for 10 minutes before putting your regulator or weighted gauge on. You need to release as much air from the canner as possible.
3. Not getting your dial-gauge tested - Even, or especially brand new dial-gauge canners can be off. Get your guage tested immediately after purchasing, and every year thereafter to stay on the safe side. Some of these canners have home test kits available. You can take your canner lid (with the gauge) into a local University Extension Office and they can test it for you. Costs may vary. *Weighted gauge pressure canners do not need to be checked or require the calibration of a dial-gauge canner.
4. Using an Instant Pot or electric pressure cooker for pressure canning - Although tempting for the sake of convenience, these are not able to be calibrated for safe canning and should be avoided.
5. False Seals - Sometimes seals don't seat properly, even when you do everything right. Leave the rings off of your jars after sealing and while storing so that if a jar does not seal correctly, you will know. When stacking jars, place a layer of cardboard or similar material between the jars to prevent from breaking seals.