Why do some jars not seal properly?
A. Jars do not seal after pressure canning for the following reasons: Jars were packed too solidly with food or were overfilled. Allow 1/2-inch headspace for fruits and tomatoes, and 1-inch headspace for vegetables, meats, poultry, and seafood. This is necessary since food expands during canning. Air bubbles were not worked out before placing the lid on the jar. Food particles were left on the sealing surface of the jar. Wipe sealing surface with a damp cloth before placing lids on jars. Air was exhausted from the canner too rapidly. Canner should be vented at a slow to moderate rate. Fluctuation of pressure during processing caused by an unsteady heat source or steam leakage. Removing or bumping the pressure regulator before the pressure has dropped completely. Pressure must always drop of its own accord. Rapid temperature changes or drafts blowing on the canner. This causes uneven pressure which forces liquid from jars. Lids were not adjusted according to manufacturer s directions.
