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Canning Jars

Source: University of Wisconsin

Standard glass canning jars are economical for home canning because with careful handling you can use them for several years. Jars come in different shapes and sizes and are tempered, or strengthened, for heat and cold.

The size you use depends on the product you can and family needs. Examine the sealing edge of each jar to make sure there are no nicks, cracks or sharp edges that would prevent a seal. Discard any jars showing these faults.

Regular and wide-mouth Mason-type, threaded, home-canning jars with self-sealing lids are the best choice. They are available in 1/2 pint, 1 1/2 pint, quart, and 1/2 gallon sizes. The standard jar mouth opening is about 2 3/8 inches. Wide-mouth jars have openings of about 3 inches, making them more easily filled and emptied. Half-gallon jars may be used only for canning very acid juices. Regular-mouth decorator jelly jars are available in 8 and 12 ounce sizes. Jars may be reused many times, but new lids are necessary each time. When jars and lids are used properly, jar seals and vacuums are excellent and jar breakage is rare.

Most commercial pint- and quart-size mayonnaise or salad dressing jars may be used with new two-piece lids for canning acid foods in a water bath canner. However, you should expect more seal failures and jar breakage. These jars have a narrower sealing surface, are tempered less than Mason jars, and may be weakened by repeated contact with metal spoons or knives used in dispensing mayonnaise or salad dressing. Seemingly insignificant scratches in glass may cause cracking and breakage while processing jars in a canner. Mayonnaise-type jars are not recommended for use with foods to be processed in a pressure canner because of excessive jar breakage. Other commercial jars with mouths that cannot be sealed with two-piece canning lids are not recommended for use in canning food at home.

Before every use, wash empty jars by hand in hot water with detergent and rinse well, or wash in a dishwasher. Unrinsed detergents may cause unnatural flavors and colors. These washing methods do not sterilize jars. Scale or hard-water films on jars are easily removed by soaking jars several hours in a solution containing 1 cup of vinegar (5 percent acidity) per gallon of water.

If you have further questions, contact your county office of the NDSU Extension Service for additional information on canning.

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