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Canning Tips – How tight should your lids be?

The canning and preserving season is well underway. Muscadine grapes and apples are ripe. Beans, beets, field peas, leafy greens, peppers and other vegetables are available. Sweet potatoes are in season; pumpkins and winter squash soon will be. For details on canning pumpkins and winter squash check out HGIC 3281, Preserving Pumpkin & Winter Squash.

When looking through some of the canning questions that we’ve been asked this summer I noticed several requests for information on the correct way to apply jar lids. So, for those of you who need clarification here’s some tips from canning expert Dr. Susan Barefoot.

To start you should remove air bubbles, check for proper headspace and wipe the jar rims. The next step is to add the two-piece lid.

Two-piece lids are recommended for canning foods.

Two-piece lids are recommended for canning foods.
Adair Hoover ©2018, HGIC, Clemson Extension

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. Do not use force or use jar tighteners when applying two-piece lids. During processing, air is forced out of the jar. If the screw band is too tight, air cannot escape. Air must be able to escape from the jar during processing; if it cannot, it can buckle lids. Buckled lids are deformed in some way by air in the jar trying to force its way out; they may not seal properly. Hot air needs to escape the jar to create a vacuum when the jar cools.

The screw band should be tightened just to fingertip tight.

The screw band should be tightened just to fingertip tight.
Adair Hoover ©2018, HGIC, Clemson Extension

A practical way to determine if the lid is fingertip tight is to place the band on the jar, turn it just until you feel resistance, then turn the band one-quarter turn more. For beginning canners, it may help to mark the band and lid with a marker at the point of first resistance and at the point that represents an additional quarter turn and to then tighten the band to that point.

So, don’t crank down those bands. If your lids are too tight, your jars may not seal.

 

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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