Preparing Jars for Canning

Step 1 - Check the Jars

Check the jars to make sure that none have nicks on the rims, cracks or sharp edges. I have used mayonnaise jars but they have had too many failures. They have thinner rims and are not as strong to handle the heat. The failure rate did not warrant using them. Often you can buy Ball, Mason, or Kerr canning jars at Goodwill or from ads in the newspaper at good prices. For applesauce we use narrow mouth jars. 

Step 2 - Wash and Rinse the Jars and Rings

Wash and rinse the jars and rings. You can use the dishwasher for this step and leave them in the machine until needed. I prefer to use quarts and narrow-mouth jars. 

Step 3 - Bring the Lids to a Boil

Before you get started with your fruits, bring the lids to a boil. After boiling, just keep them in the water. One hint: as you place the lids in the small pan, alternate the lids with the tops and bottoms in opposite directions. This will keep them from  sticking together. Some cooks recommend not boiling the lids, but to bring them to 190 degrees. I have found that too much trouble, trying to get them to the perfect temperature, so I just bring them to boiling rather. Don't boil them for a long time, just bring them to boiling and remove them from the stove.

Step 4 - Boil the Jars

Boil the jars before you fill them. You should put the bottom-side down in the pan with about an inch of water on slow heat. You need to do two things here. First, you need to sterilize the jars and secondly, you want the jars hot as you fill them with cooked fruits. This will prevent the jar from breaking. You never want to put boiling liquid into a cold jar. I put them on a slow heat as I work to prepare the fruit. Watch to make sure you don't run dry in the pan. Sometimes the water will be drawn up into the jars and leave the pan dry. Simply tip or lift the jar to let the water out.

Step 5 - Fill the Jars and Wipe the Rim

With a clean damp cloth, wipe the rim of the jars to remove any spilled fruit on the rim. If the rim of the jar has something on it, you may experience a sealing failure.

Put on a lid, start the ring on the jar, and then tighten the ring. Tighten firmly, but not with all your strength

Step 7 - Process the Jars

Process pints and quarts in a water bath for 20 minutes.  Water-bath canners are usually made of aluminum or of porcelain-covered steel. They have removable perforated racks and fitted lids. The canner must be deep enough so that at least one inch of briskly boiling water will be over the tops of the jars during the processing. To ensure uniform processing of all jars with an electric range, the canner should be no more than 4" wider in diameter than the element on which it is heated. For the water bath, the timing starts after a full boil.  For a water bath, you should not put cold jars in hot water or hot jars in cold water. Do not retighten lids after processing the jars.

Step 8 - Let the Jars Cool

Remove the jars from the water bath and place them on racks, towels, or newspapers to cool at room temperature for 12-24 hours. Do not tighten lids at this time. The jars should cool until the next day. The food level and liquid volume of raw-packed jars will be noticeably lower after cooling. Air is exhausted during processing and food shrinks. If a jar loses excessive liquid during the processing, do not open it to add more liquid. 

Step 9 - Testing the Jar Seals

After cooling the jars, remove the screw bands and test the seals by one of the following options:

Option 1: Press the middle of the lid with a finger or thumb. If the lid springs up when you release your finger, the lid is unsealed.

Option 2: Tap the lid with the bottom of a teaspoon. If it makes a dull sound, the lid is not sealed. If food is in contact with the underside of the lid, it will also cause a dull sound. If the jar is sealed correctly, it will make a ringing, high-pitched sound.

Option 3: Hold the jar at eye level and look across the lid. The lid should be concave (curved down slightly in the center). If center of the lid is either flat or bulging, it may not be sealed.

If the jars are sealed, wash the jars in warm soapy water. I recommend marking the lid with the year and store the jars in a dark cool place without a ring. If rings are left on, they often corrode and make it difficult to open. You will also need the rings for the next canning job. But when you open the jar, you will then need to put a ring back on to keep the jar sealed and able to refrigerate what is not used at the first opening.

Step 10 - Reprocessing Unsealed Jars

If a lid fails to seal on a jar, remove the lid and check the jar-sealing surface for tiny nicks. If necessary, change the jar, add a new, properly prepared lid, and reprocess within 24 hours using the same processing time. Headspace in unsealed jars may be adjusted to 1-1/2 inches and jars could be frozen instead of reprocessed. Foods in single unsealed jars could be stored in the refrigerator and consumed within several days.