When you remove hot jars from the canner, use a jar lifter, or protect
your hands with cooking mits, pot holders or canvas gloves. Set the jars
upright to cool on a rack, such as a cake rack, or a bread or cutting
board, with double layers of dry cloth or newspapers beneath the jars.
If jars are placed on a cold surface or wet cloth, the difference in
temperatures may cause the glass to crack.
Avoid placing jars in a draft, but leave two or three inches between
them so air can circulate freely. Avoid further tightening of lids that
have sealing compound, since this usually breaks the seal--unless the
lid manufacturer states it is safe to tighten.
If your processing temperature was not held steady and liquid boiled out
in processing, do not open the jar to add more. Leave the sealed jar
just as it is.
Do not cover jars because this slows down cooling and food continues to
cook. If you have an air conditioning vent that will direct cold air on
jars, cover the vent during this canning session.
After 12 hours, check the seals. The vacuum may cause a loud snap of the
two-piece vacuum seal while it cools, which is an indicator of an
airtight seal. If the center of the lid holds down when pressed and the
lid does not move, it is sealed.
Tap the center of the lid with a spoon--a clear, ringing sound indicates
a good seal; a thudding sound indicates the possibility of an imperfect
seal.
If there is a sealing failure, you will need to reprocess the jars.
Remove the lid, heat the food and liquid, fill a clean jar and use a new
lid. Process the full length of time. If only a few jars did not seal,
you may elect to refrigerate and use the food within a day or two or
freeze it.
Once the jar is sealed, allow it to set until cold. Then remove the
screw ring band, wash and store in a dry place for reuse. For safety
make a routine check of canned foods each month.