Pressure Canner Checklist

Check that all canner parts are in good condition.

• Handles should be secured tightly with no loose, broken, or missing parts.
• Does the canner have its canning rack? Jars must be off the bottom of the canner during processing to reduce stress on the glass. A rack can be made by tying jar rings together and placing in the bottom of the canner. A round metal cooling rack is also a good substitute. 
• Use the original weight or pressure regulator. If your canner has a petcock, determine that it opens and closes correctly.

Replace a cracked or worn gasket.

• Under normal usage gaskets should be replaced every three years. The intense heat of pressure canning may cause the gasket to shrink, allowing air and steam to escape under the lid.

• Determine that a replaced gasket is the correct size. Ascertain the make and model number of your pressure canner. A gasket will likely fit several models. You cannot determine the correct gasket by appearance. The gasket needs to fit firmly around the edge of the lid with no gaps that would allow steam to escape.
• Replacements parts are available in some stores where canners are sold. Parts can also be ordered online.
• Replacements parts are available for canners that were manufactured recently. However, it is becoming increasingly difficult to obtain parts for older canners, especially ones that use the thin flat gasket.

Replace the over pressure plug when you replace the gasket. 

• An over pressure plug is most likely included in the package with a replacement gasket. Some packages come with two models of pressure plugs and you must determine which matches the one on your canner. To replace the over pressure plug, press the old one out of the lid from the top of the lid to the inside. Then replace it by pressing the new plug with the convex side up through the hole from the bottom to the top of the lid.

Clean the vent tube.

• Run a pipe cleaner through it. A clogged vent tube can cause a build-up of pressure inside the canner that is not registered on the dial or it can prevent the weight from jiggling. Both situations can cause the pressure release valve to blow.

Have the dial gauge tested annually for accuracy.

• Call your local Penn State Extension office to determine where you can get it tested and to schedule an appointment.

Replace the dial gauge.

• Replace if the dial gauge is cracked, rusted or the glass is missing or if testing indicates the pressure is off by more than two pounds. 
• If it tests off by 2 pounds or less, make adjustments in the pounds pressure used for processing. 

Check the weight on a weighted gauge canner. 

• The weight on a weighted gauge canner should move or "jiggle" freely.
• If not, check that the vent pipe is clear as described above or check that it is the weight that came with the canner. 
• Weights are not interchangeable from one canner to another or from a pressure cooker to a canner. 
• Read your instruction manual to determine how frequently the weight should jiggle. Some only jiggle 3 or 4 times a minute; others jiggle continuously.

Clean that gasket trough.

• Whiting powder (calcium carbonate) can be used as a scouring powder to remove built-up grease.

Clean the canner regularly. 

• Never immerse the dial gauge in water. 
• Dry the canner and store it with crumpled paper towels in the bottom to help absorb moisture and odors. 
• Wrap the lid in paper and place it upside down on the canner to allow air to get into the canner avoiding mustiness.

Remove the dark surface of an aluminum canner.

• Fill it above the darkened line with a mixture of one tablespoon cream of tartar to each quart of water. 
• Place the canner on the stove, heat the water to a boil and boil covered until the dark deposits disappear. 
• Empty the canner, wash it with hot soapy water, rinse and dry.

Discard recipes in old canner manuals. 

• Directions in canner manuals published before 1994 may have inadequate processing times or pressures to destroy harmful bacteria.
• Use research-based recipes published since 1994. 
• Recommended resources are the USDA Complete Guide for Home Canning, updated 2015; So Easy to Preserve, 6^th edition; Penn State Extension's Let's Preserve fact sheets and the National Center for Home Food Preservation .

Additional information

• Penn State Extension's Let's Preserve: Basics of Home Canning provides detailed information on pressure canning.
• The amount of water (2 to 3 inches) to add to the bottom of the pressure canner depends upon the length of the process time. Longer process times require more water as minute amounts of steam are released throughout the process.
• Center the canner over the burner.  Select an appropriate size burner. Canner should not extend more than 2 inches beyond the burner.
• After the canner is vented for 10 minutes, and the pressure regulator or weight is applied to the vent pipe, the canner will reach pressure in 3 to 10 minutes. As pressure reaches 9 pounds, reduce heat slightly and gradually bring to 10 pounds (weighted gauge) or 11 pounds (dial gauge). Waiting until the desired pressure is reached to reduce the burner heat will result in the pressure continuing to rise. Note: Over-processing is not a safety issue but may over-cook the food.
• Loss of pressure at any time can result in under-processing or unsafe food. Start processing time over if pressure goes below designated level.
• Large pressure variations during processing can cause liquid loss from jars.

References

Andress, E. & Harrison, J.; So Easy to Preserve, 6th edition. Bulletin 989. (2014, revised 2020). University of Georgia. 

LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, March 1). "Let's Preserve: Basics of Home Canning". Penn State University. 

National Center for Home Food Preservation. (n.d.) University of Georgia.