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University of Illinois Extension

Cooling Jars & Testing Seals

Cooling Jars

  • Using jar lifters, remove jars from canner
  • Place jars on a dry cloth, cutting board or rack, away from draft
  • Let jars sit undisturbed for 12 to 24 hours
  • Lids make a “clicking” sound as they seal

Testing Seals

  • Lids won't move when pressed
  • Clear ringing sound when tapped
  • Lid curved inward (concave)
  • Remove screw bands and wipe jars clean
  • Use vinegar to remove white mineral deposits on jars
  • Label using CFO labeling guidelines (See Food Labeling and Placards)

Testing for Seals