How to Seal Glass Canning Jars

Preserving food by canning is a time-honored tradition that works perfectly when done right. Canning is a process that seals in flavor and preserves food in a sterile environment. Canning jars are designed with a seal and ring that will suction onto the jar when the air is removed from the container. You can use vacuum seal units to preserve food, but the traditional way is the boiling water method. Always test the tops of canning jars after sealing them to ensure the top has no bubble, which would indicate it is not fully sealed and the food could spoil.

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You can reuse canning jars over and over after sterilization but need new seals every time.

Step 1

Run the jars and rings through the dishwasher. Put the canner or pot on the stove filled with water; let water come to a boil. Use the tongs to put the jars in the boiling water to sterilize them. Let the jars sit in the boiling water for 10 minutes, then remove them onto a clean dish towel. Turn the burner off but leave the canner and water for sealing the jars.

Step 2

Inspect the canning rings to ensure none of them are bent or broken. Imperfectly fitting lids will not seal. Make certain all the rings and seals fit the size jars you have.

Step 3

Fill the jars with the preserve item up to 1/2 inch from the top. Push a spatula or butter knife along the inside of the jar to release bubbles. Wipe the tops of the jars with a damp towel. Place the seal on top of the jar, then screw on the metal ring. Do not overtighten, but screw ring on until it stops naturally.

Step 4

Place the jars in the canner and turn on the heat. The water should cover at least 2 inches of the jars. Bring the water to a boil. Place the lid on top and boil for at least 10 minutes, up to 30 minutes. The time depends upon the type of preserved item. Follow the guidelines that come with the canning seals.

Step 5

Turn off the heat after the allotted time and remove the lid. Be careful of the steam. Use the tongs to remove the hot jars and place them on a dish towel to cool. Allow them to cool overnight, then check the seals for bubbles. Label and date your canned goods and store in a cool dark place.