Calibration

• Each year you must have the gauge on your pressure canner tested for calibration. Gauges that are out of calibration cannot be depended on to safely process food. If the calibration is off, you should check with your manufacturer to see if they can re-calibrate it for you. You will probably have to pay for the service and the shipping. If you cannot afford the cost, there may be local merchants in your area who can re-calibrate your pressure canner gauge for a lower price.
  
  

Gaskets

• Most pressure canners use gaskets which prevent steam from escaping during food processing. It's important to keep these gaskets clean and in good working order at all times. Steam leakage will make it very hard for your pressure canner to reach the ideal pressure. If your gasket is stretched out, dried out, bent, or nicked, you should replace it with another one.
  
  

Venting

• Before pressurizing your canner, you need to vent it so that no air is trapped inside while you are processing. If air is trapped inside, under-processing may occur because of the trapped air resulting in a lower temperature. You should vent your canner according to the manufacturers directions for 10 minutes prior to pressurizing.