Frequently Asked Preservation Question: Buckling Lids

When buckling occurs immediately after heat processing, the band may have been applied too tightly. During processing air inside the jar expands and venting must take place to allow air to escape and create a vacuum seal when the jar cools. If the ring band was applied too tightly on the lid, a buckle forms as the air forces a path to escape. Adjust the band using only your fingertips. Avoid turning with the full force of your hand or wrist. Turning the lid too tightly can cause the sealing compound to be cut preventing a seal. If a jar with a buckled lid seals, mark it and plan to use it first.

When buckling occurs during storage, the cause is food spoilage. Heat processing has been inadequate to destroy all spoilage microorganisms which then produce gasses inside the jar. The lid may bulge or it may actually break the seal. Do not use jars of food that unseal while in storage or that shoot out gas or liquid when opened.

Reference:

Andress, E. & Harrison, J.; So Easy to Preserve, 6^th edition. Bulletin 989. (2014, revised 2020). University of Georgia.