Why Canning Lids Buckle?

During canning, air trapped in the headspace between the bottom of the lid and the top of the food is forced out of the jar. When lids are too tight, the air cannot easily escape so it forces its way out by deforming the lid. This leads to the buckling or crinkling effect.”

How tight should lids be when canning?

According to So Easy to Preserve, “When using two-piece lids, place the treated lid on the filled jar, center it, and hold it in place with fingers. Then screw down the band fingertip tight. These lids should not be tightened further after processing.” The screw band should be tightened just to fingertip tight.

Why are canning lids in short supply in 2020?

It all began last year when the pandemic hit in early 2020. Stuck at home, people picked up gardening, then canning their harvest. “That led to a supply shortage of canning lids,” said Suzanne Driessen, University of Minnesota Extension food safety educator.