If you are a home canner, you know that all the expenses associated with doing so add up over time.
Sure, the return on your investment is often great since you are preventing food waste, but anything that canners can do to further drive down costs is usually a step worth taking.
This usually begins with jars and lib components. How about the lids? Can you reuse canning lids?
No, canning lids are not reusable. The metal disk lined with a sealing compound is designed to create an airtight seal that can only be achieved once. After that, the disk is no longer able to grip the jar’s rim as tightly, so it can’t properly reseal the contents.
The bands are reusable, however, as are specialty lids with permanent gaskets intended for multiple uses.
Now, some people choose to reuse canning lids anyway, but it’s not recommended.
Not only is there a chance that your food won’t be properly sealed (and could thus dangerously spoil), but also reused lids may not fit correctly on the jars from the start and could cause them to break during the canning process.
There is a lot more to learn and to consider about this problem, however, so keep reading.
“Lids” are Multi-part Components
Your typical canning lid is not a one-piece item. Instead, you have two parts that must work together to form a useful seal on a jar and its contents: the band and the disk.
The band is a simple, threaded metal ring that helps to hold the disk in place over the mouth of the jar. The disk is a flat piece of metal lined with a sealing compound on the underside.
When heated during the canning process, this compound softens and forms an airtight seal between the disk and the lip of the jar, held in place by the band.
Once cooled, the seal should last indefinitely, at least until disturbed.
Bands are Reusable, Disks are Not
You can reuse the metal bands as often as you like, practically. In fact, you may never need to replace them unless they become damaged or lost.
True, they do wear out over time from the stresses associated with canning but this is comparatively rare.
The same cannot be said for typical disks, however. These are, invariably, one-and-done items.
Once they have been used for a single-sealing cycle, they will hold until such time as you open the jar and its contents, then they should be discarded.
Trying to use them again, even once, dramatically increases the likelihood of failure and spoilage.
Why Can’t You Reuse Disks?
The sealing compound disks are designed for single use only. Once heated and cooled, the soft sealant compound loses its ability to properly reseal a jar on the next cycle.
Additionally, the disk may no longer fit as snugly on the rim of the jar, which could lead to breakage during the canning process.
Reusing the disks is not worth the risk, given how inexpensive they are to replace. Yes, they are one of the primary “consumable” expenses of canning, but there is not much to be done about it except switching to a new lid and possibly new jars. More on that later.
A Used Disk may Seal Tightly, but the Seal Will Still Likely Fail
To clarify, it is entirely possible that a disk will still seal a jar tightly enough beneath a ring to make it leak proof or even airtight, for a time.
This might well mean they are serviceable enough for a task that does not require vacuum sealing from the normal canning process.
For example, if you were to use a used disk to cap off a bottle of vinegar or oil, it might well hold for years without issue. The same could be said for any number of other liquids where a truly airtight seal is not required.
The problem is that the reused disks are not going to form a reliable or strong enough seal for canning anymore.
If you want, you can keep your “once-used” disks for all sorts of other tasks, in and out of the kitchen, but if you are wise you will not employ them any longer for canning.
Though it is true that plenty of canners report anecdotal success with reusing disks, it is not something we would recommend.
The body of evidence, both long experience and repeated failure, is too great to ignore, and the risks are too great: you and yours could risk exposure to botulism over a disk costing a few cents.
Can You Reapply Fresh Compound to the Disk?
Technically, you could, but this is not recommended, not at all. It is certainly a messy and difficult proposition.
The new sealing compound will not adhere as well to the metal as the factory-applied stuff did.
Keep in mind that sealing compound is not just wax or glue from a tube; it is a complex mixture of ingredients designed to work in combination with the metal and glass, when heated sufficiently, to create an airtight seal.
Applying it at home will not give you the same results as the factory-applied stuff, that’s for sure.
Even if you could manage to apply it evenly and thinly enough (a big “if”), there’s no telling how well it would work.
You could end up with a batch of failed seals, which is the opposite of what you are trying to achieve by canning in the first place.
A Wiser Strategy: Use New Disks Every Time
The wisest and safest strategy, as we have said all along, is to use new disks every time you can. They are not that expensive, and the peace of mind is worth it. You will be able to see if the disk is properly sealed to the jar, so there is no need to worry about whether or not the contents are safe.
Reusable Lids Can be Used Over and Over
While standard canning lids are designed for single use only, there are some permanent gasket-style lids on the market that can be used multiple times.
These have a silicone or rubber ring instead of a compound disk, and they can be used over and over until their solid seals start to degrade, at which point they must be thrown out.
Depending on the type and brand, they will be either a two- or even three-piece lid. You will need to buy these separately for your existing jars, assuming they are compatible or else purchase new jars for the purpose.
If you are dead set on using your disks over and over, you are well-advised to invest in a set of reusable lids.
The upfront cost is higher than one-use disks, but these will last a long time with proper care.
Always Inspect Lid Components and Jars for Damage
Keep in mind, a used disk might not be the failure point in the system. If your jars are old, hairline cracks and stress could have taken their toll.
The metal bands could be corroded or damaged, making it difficult or impossible to get a tight, good seal with the disk.
The threads on the band or jar might be eroded or stripped as well, making it hard to screw on the rings tight enough in the first place. New disks can be defective from the factory, though this is rare.
Inspect your jars and lids for any damage before beginning the canning process, and don’t assume that other canning components besides the disk will last indefinitely. Everything wears out eventually!
Tom has built and remodeled homes, generated his own electricity, grown his own food and more, all in quest of remaining as independent of society as possible. Now he shares his experiences and hard-earned lessons with readers around the country.