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Canning -- Miscellaneous

What causes buckled lids?

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Buckled lids appear to warp, bulge, or crease upward near the outer edge. Ball brand and Kerr brand two-piece vacuum lids are made to release pressure by venting air from the jar after processing and upon cooling. When the lid does not vent, pressure build-up warps the lids and prevents a good seal. There are several potential reasons for this to occur: Applying the screw bands too tightly causes buckling that is apparent immediately after processing. Boiling the lids softens the sealing compound too much, resulting in a premature seal. Food spoilage due to incorrect processing produces gases inside the jar that force the lid to buckle or unseal. Preventing buckled lids is simple. Always process foods using up-to-date guidelines, prepare lids according to manufacturer?s instructions, and apply bands just until a point of resistance is met ? fingertip tight. Source: Original FAQ posted at

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