What to Do If Mason Jars Don’t Seal Safely

Leave processed mason jars upright and undisturbed for 12 to 24 hours. Then remove the screw band and press the center of each lid; a sealed lid should be concave and should not flex or click. If the lid moves, treat the jar as unsealed.

Refrigerate an unsealed jar immediately and use the food within several days, or freeze it in a freezer-safe container with adequate headspace. Do not store an unsealed jar at room temperature, even if the lid appears partly attached.

If you discover the failed seal within 24 hours, transfer the food to a clean jar if the original rim is chipped or damaged. Fit a new prepared lid, adjust the headspace as directed by the tested recipe, and repeat the entire water-bath or pressure-canning process.

Before filling, inspect the jar rim for chips, wipe it clean, and tighten the band only fingertip-tight. Food residue, insufficient headspace, trapped air, incorrect processing time, or an overtightened band can prevent sealing. For more information about jar features and everyday storage, see this vintage embossed glass storage jar guide.