Billie says: Help!! Did a double stack canner of pint green beans. I can tell for sure 3 of the top ones the Lid is buckled UP on one side .....??????
When buckled lids appear to warp or bulge upward under the screw bands.
There are several causes:
1: Buckling that is apparent immediately after heat processing is caused by application of the screw bands too tightly. Two-piece home canning lids are made in two pieces for a very important reason: To release pressure and vent air from the jar during heat processing.
As the filled jar is heated, headspace pressure increases until excess air is vented from the jar. When the band is applied too tightly, there is no way for air to be exhausted from the jar. Consequently, the pressure build-up warps the lids and disrupts the seal formation
2: If you boil the lids and soften the seal too much it may cause you to get a premature seal.
3: If they bulge later on the shelf, it could be that the food has spoiled due to being processed wrong or for the wrong length of timeand gases have formed in the jars either warping the lid or breaking the seal.