Prepare for Canning Season



Writing for the Iowa State University Extension and Outreach Answer Line on April 4, 2023 Marlene Geiger discussed the importance of your pressure canner and the need to test the dial gauges for accuracy every year. Marlene holds a B.S. in Home Economics Education and Extension from the University of Nebraska-Lincoln, as well as an M.S. in Textiles and Clothing from Colorado State University. Her favorite pastimes include, gardening, quilting, cooking, sewing, and sharing her knowledge and experiences with others. Her well researched article will help you have a successful canning season. Because her article is so helpful and so well researched, we have included it here in its original and unedited form below.

Dial Gauges Must be Tested Annually for Accuracy

Most of today’s pressure canners have either a dial gauge or weighted gauge for indicating and regulating the pressure. There is one exception; the All American brand has both a dial and weighted gauge. For canners having a dial gauge, safe canning beings with getting the gauge checked for accuracy yearly or before the start of the canning season. A dial gauge has movable parts which can go out of calibration. Gauges that read high cause under-processing and may result in unsafe food. Clostridium botulinum bacteria are the main reason why low-acid foods must be processed with the correct pressure and time to be safe. Gauges with low readings may cause over-processing which is not a food safety issue, but rather a food quality issue. Pressure adjustments can be made if the gauge reads 2 pounds high or low. Gauges testing more than 2 pounds of difference, should be replaced. The dial gauge should also be checked if any of the following conditions exist: cover has been submerged in water or dropped, gauge lens is broken or has fallen out, parts are rusty, pointer is not on “0”, or for any reason you believe the gauge may not be accurate.1 The dial should be replaced if it is cracked, rusted, or the glass is missing. Gauges on new canners and replacement gauges should be tested before use.

Weighted gauges do not require testing for accuracy because they cannot go out of calibration.

Dial Gauge Testing Services

There are several services that provide dial gauge testing.

Local County Extension Office – Many County Extension Offices have the equipment and trained personal for testing the National (National Pressure Cooker Company), Magic Seal (sold by Montgomery Ward), Maid of Honor (sold by Sears, Roebuck and Company), or Presto® brands. Check with you local office for availability or to find out about testing events in your area. AnswerLine (800-262-3804 or 515-296-5883) can help residents of Iowa and Minnesota find a location for testing in your area.

Presto – National Presto Industries will test dial gauges at no charge provided it is one of the following brands: National (National Pressure Cooker Company), Magic Seal (sold by Montgomery Ward), Maid of Honor (sold by Sears, Roebuck and Company), or Presto®. Check out the Care and Maintenance Guide at for information on how to send a gauge for testing.

Hardware Stores – some hardware stores also offer this service. Call before you go.

All-American – For testing of All-American dial pressure gauges, contact Wisconsin Aluminum Foundry, 920-682-8627. The weight is more accurate than the gauge and customers should use the weights to attain the correct pressure. If the weight begins to rock at the desired pressure and the gauge is off by more than 2 psi the company recommends replacing the gauge. The gauge is primarily used as a reference to know when the unit is at 0 psi and can safely be removed and the canner opened.2

Canner Manufacturers – For pressure canner brands not aforementioned, contact the manufacturer of the unit.

After testing is complete, you will get a Canner Dial Gauge Testing Report or similar. It is a good idea to keep the reports for reference.

In addition to getting dial gauges checked, there are a number of other items to check out to make sure that the canner is in good working order for canning season. If any of the following do not check out, they should be replaced or cleaned as needed.

Replacement Parts

Replacement parts are available at some hardware stores or stores that also sell food preservation equipment. Parts may are also be purchased directly from some of the manufacturers. The Pressure Cooker Outlet has replacement parts for many makes and models of canners. Parts can also be found at Be sure to know the canner model number and part number of the needed item (may be found in the canner manual). The model number can be found on the bottom of the canner, the handle, or the lid.

Start the canning season off right. Get the gauge tested and make sure that your canner meets all check marks.

Sources (accessed 21 February 2023):

1Care and Maintenance Guide. National Presto Industries.

2Zepp, Martha. 23 May 2018. Pressure Canner Dial Gauge Testing. PennState Extension.

Botzek-Lin, Deb with Suzanne Driessen and Glenyce Peterson-Vangsness. 2021. Testing Dial Pressure Canner Gauges. University of Minnesota Extension.

Braun, Curtis with Megan Erickson. 6 October 2022. Testing Dial Pressure Canner Gauges. South Dakota State University Extension.

Pressure Canner Manuals.

So Easy to Preserve, 6th Edition. Publication 989. Cooperative Extension. The University of Georgia.

USDA Complete Guide to Home Canning (2015). USDA National Institute of Food and Agriculture.

Zepp, Martha. 21 May 2020. Pressure Canner Checklist. PennState Extension.