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Canning -- Miscellaneous

What causes a lid to become corroded or rusted while it is on a jar of home canned food?

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Following the manufacturer?s instructions for preparing and using lids will reduce the possibility of corrosion. It is also important to use home canning lids that have been stored in a cool, dry, dark place. If corrosion does occur, one of the following factors may have been the cause: not preparing lids for use according to manufacturer?s instructions; scratch in the enamel surface of lid; incorrect headspace; strong concentrations of salt or acid; improper storage of lids prior to canning; not removing bands before storing sealed jars; not wiping off lid and jar surface with a clean damp cloth to remove food particles and residue. A jar of home canned food with a lid that becomes spotted with rust may be used as long as it was properly processed using up-to-date methods (see Canning Basics), and there is a vacuum seal on the jar. Please note this applies to surface spots only. Source: Original FAQ posted at

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