Here are the three most frequently asked questions about canning lids.
Q. Can I reuse my canning lids?
Canning Supplies
A. No, you always want to use brand, new lids each time you do home canning. Using new lids is the only way to ensure getting a proper seal on your jars.
Q. How can I tell if the lid is sealed on the canning jar?
A. After you have processed your canning jars full of food you will want to allow them to cool. During the cooling process you will hear a ping. This is an indication the lid is sealed. The lid will also be depressed in the center. If a canning lid is still raised and when you press on it, it goes up and down, then you do not have a good seal. Another way to check for a good seal is to remove the band and lift the jar using only two fingers on the edge of the lid. If the lid stays on you have a proper seal.
Q. How can I get a good seal on my canning jar?
A. First, make sure you always use brand, new lids. Second, wipe the rim of the jar after you have ladled your food into the jar and before you place the lid on. If there is any food residue on the rim you will not get a proper seal. And third, do not over-tighten the bands. Use only your thumb and one finger when screwing on the bands to avoid tightening them too much. Bands that have been over-tighten can also cause a jar not to seal properly.