Home canning requires jars, lids, and rings (metal screw bands). You place the food in the jar, position the metal lid on with the gasket side down, screw on the ring, and then process your jars. After you remove the jars from the canner, some of the lids will already have formed a vacuum seal and others will make a popping sound as the vacuum forms a few minutes later as they cool down. You then leave them alone for 12-24 hours, at which point they are ready to store.
So the burning question is: do you store the jars with the rings off or on or does it even matter? My mother stored them both ways, as I often have, too. I always thought this was because most people end up with more jars and lids than rings (jars initially come with lids and rings if you buy them new; after that you just buy replacement lids, unless you buy the jars used, in which case they will usually come with no lids or rings).
However, I’ve read on several sites that you should always store home canned goods with the rings off. For example, Jennifer at Self-Reliant School advises:
Remove the rings. If the rings stay on and the lid fails (becomes unsealed) while the ring is on, the lid may reseal itself. However, bacteria has already invaded the jar and the food should not be eaten; with the ring left on there is no way you will know about the resealing. If the rings are off the lid has no pressure to reseal itself so if the lid seal fails then you’ll know and you can throw that jar out.
I thought about that for awhile, and I wondered if a lid could really re-form a vacuum seal just from the pressure of a ring. I looked on the websites of the major manufacturers, but I couldn’t find any specific recommendations about this.
The National Center for Home Food Preservation says to store jars with the rings off:
If lids are tightly vacuum sealed on cooled jars, remove screw bands, wash the lid and jar to remove food residue; then rinse and dry jars. Label and date the jars and store them in a clean, cool, dark, dry place. For best quality, store between 50 and 70 °F. Can no more food than you will use within a year.
Do not taste food from a jar with an unsealed lid or food that shows signs of spoilage. You can more easily detect some types of spoilage in jars stored without screw bands.
So according to the government experts, you should store them with the rings off, but only because it is easier to detect a failed seal, not because a failed lid can reseal itself. But I still wasn’t sure about that, so I decided to contact the Ball-Kerr company directly to see what they had to say. Here is their reply to me:
Thank you for contacting us- hopefully we can help set the record straight regarding our suggested methods of storing your jars.
Although many of our consumers do choose to store their jars with the bands on, we don’t recommend doing so for two reasons. The first relates to the mechanism of the two-piece lid. The two-piece lid, initially marketed by the Kerr brand in 1915, is recommended for use due to the ease of determining seal quality. When spoilage occurs, gas builds up in the jar- the resulting pressure will cause the lid to come unsealed or pop.
Since the lid seals via an integrated gasket on the rim of the jar and the band grips the jar from a position below the rim, leaving the band on can indeed hold the lid to the jar when it shouldn’t be and make it appear sealed although spoilage has occurred. Earlier one-piece lids sealed on the bead or the shoulder of the jar –below the threads and rim- and thus couldn’t indicate a comprimised seal.
The second reason we don’t recommend storing your jars with the bands on is that it can, in some cases, impact the lifespan of your bands. Moisture that may be caught between the band and jar can cause the bands to corrode prematurely.
We hope this information helps! Please let us know if you need clarification.
The Consumer Affairs Team
So there you have it: store your jars with the rings off so that if the lid seal fails, you’ll know it right away. But if you store them with the rings on, when you take the ring off, just check that the lid is still vacuum-sealed onto the jar; if it is, then the seal has not failed because it cannot reform once it fails (but still check the contents of any jar with a visual inspection and a sniff whenever you open a new one).