I did something the internet told me to. Now what.
Sources last opened 2026-08-26.
The short version
Start here: you are reading this because you got a doubt and went to check. That is the behaviour that keeps people safe in this subject, and it is worth more than never having doubted at all.
Now sort what you have into one of three situations, because they have genuinely different answers. The jar did not seal — the guide gives you three tested options and you have a 24-hour window for one of them [F-9.9]. The jar sealed but the method has no tested process behind it — a seal test cannot help you here, and the honest answer involves the refrigerator, the freezer or the bin rather than a rescue. Somebody has already eaten some — that is the one situation on this site where the answer is not a kitchen answer.
What is not on this page is a way to fix a jar after the fact. There is no tested process for re-canning already-canned food, and NCHFP says so plainly [F-9.7]. I would rather tell you that than invent something reassuring.
First, the thing nobody says
The page you followed was not obviously bad. It had photographs, a comments section full of people saying it worked, and a byline. It probably ranked above the Extension service that says the opposite, because Extension services write like Extension services and the other page was written by somebody who understands headlines.
You followed it, and then something made you check, and the check found a problem. That sequence — doubt, then look it up, then act on what you find — is the entire safety mechanism in home canning outside of a laboratory. It just ran correctly. Whatever happens next with these particular jars, that is the outcome you wanted.
So: no lecture here. Three situations, and what each one actually offers.
Situation one: the jar did not seal
The easiest of the three, and the one with real tested options.
Take the lid off and run a fingertip round the rim looking for tiny nicks. Change the jar if you find one. Then choose: a new lid and reprocess within 24 hours using the same processing time, or adjust the headspace and freeze it, or put a single jar in the refrigerator and eat it within several days [F-9.9].
The 24-hour window applies only to the first option. Freezing and refrigerating have no deadline of that kind, and neither is a lesser outcome.
One caveat, and it is the reason this section is short. This passage assumes the process itself was right and only the closure failed. If the method had no tested process behind it, reprocessing does not apply, and you are in the next section instead.
Situation two: it sealed, and the method has no tested process
This is the harder one, and the honest answer has three parts.
A seal test will not help. Every test in the guide measures the vacuum [F-11.1]. Jars closed without processing seal perfectly well, and the bacteria in them are not destroyed [F-10.2]. A good seal here is not a partial pass.
Re-canning is not a repair. There is no tested process, and the reason is physical: already-cooked food packs differently and heat reaches the centre differently, so the times written for fresh food do not transfer [F-9.7]. See the notice below.
What is left is the refrigerator, the freezer, or disposal. If the jars are fresh out of the canner, treat the contents as cooked food and use them accordingly — that is my judgement, not a published procedure, and it is available precisely because neither refrigeration nor freezing needs a tested schedule.
If the jars have been stored, do not open them to assess them. A suspect low-acid container is handled as though toxin is present, which is the guide's rule rather than an abundance of caution [F-11.7], and the disposal procedure differs depending on whether the jar is still sealed. It is quoted in full on Botulism: what to actually do [F-11.8].
And if the food is one where the tested position is unambiguous — plain vegetables in a boiling water bath, dairy, purées, cake batter in jars — the reasoning behind each is in what not to can, sorted by which kind of "no" it is.
Situation three: somebody has eaten it
Stop reading canning pages, this one included, and read Botulism: what to actually do.
Two things worth carrying there with you. It is rare — most jars canned by untested methods do not make anyone ill, which is exactly why the methods keep circulating. And the symptoms are unusual enough to be recognisable, which is the reason that page exists at all.
What to do about the next batch
Not much, and none of it is punitive.
Get the schedule for the specific food from NCHFP or your state Extension service, in the equipment that schedule was written for [F-9.7]. Check that the recipe you are following names its source rather than saying "USDA-approved" in the abstract. And keep the smallest possible note of what you did — food, jar size, method, pressure, time, date — because the four process conditions in USDA's boiling exemption are all questions about the past [F-11.3], and a two-line note answers them in a year's time when your memory will not.
That note is also what makes the difference between this situation and the same situation next autumn. The reader who can say exactly what they did has a decision to make. The reader who cannot is guessing, and guessing is what got the jars on the counter.
If the jar did not seal: three options, all tested
If a lid fails to seal on a jar, remove the lid and check the jar-sealing surface for tiny nicks. If necessary, change the jar, add a new, properly prepared lid, and reprocess within 24 hours using the same processing time. Headspace in unsealed jars may be adjusted to 1-1/2 inches and jars could be frozen instead of reprocessed. Foods in single unsealed jars could be stored in the refrigerator and consumed within several days.
USDA Complete Guide to Home Canning, 2015 revision, p. 1-26
The link above opens the document itself, so a printed page number leads somewhere. What this document is, and who maintains it.
Opened and read by this site on 2026-08-26.
This is a rare passage and worth noticing for what it is: the tested source handing you a way out, with three routes and no lecture attached.
Reprocess within 24 hours. Check the rim for tiny nicks, change the jar if you find one, fit a new lid, and run it again using the same processing time as before. The 24 hours is the part to hold on to — this option has a deadline.
Freeze it instead. Adjust the headspace and the jar goes in the freezer. No canner, no schedule, no deadline.
Refrigerate a single jar and eat it soon. Several days, as ordinary leftovers.
All three are in the guide, and none of them is the consolation prize. If it is late and you do not want to run the canner again, freezing is a completely legitimate answer to a jar that did not seal.
Note the limit of this passage, though. It is about a jar that failed to seal after a correct process. It is not a repair procedure for a batch canned by a method that had no tested process to begin with, and it does not become one.
If you were hoping to just run it again properly
(1) We have no safe tested processes to do this. In some cases, the way the heat is distributed throughout the jar during canning will be very different if you start with already canned/cooked food than with fresh. Excessively softened foods will pack more tightly into a jar, or arrange themselves differently and the process time recommended for fresh foods will not be enough for the already canned foods.
Without tested processes for re-canning foods, there is no way to know how to reduce the canning process and the default (although not a recommendation) is to process for the full time and temperature as if starting from scratch.
Opened and read by this site on 2026-08-26.
One sentence carries this: we have no safe tested processes to do this.
Then the mechanism, which is the part that makes it more than a policy. Heat travels through a jar by moving through the food, and how it moves depends on how the food sits. Food that has already been through a canner is softer, so it settles tighter or differently, and heat reaches the centre more slowly than it did in the jar the schedule was written for. A number that was adequate for fresh food is not automatically adequate for the same food in its second pass.
Note what NCHFP is careful about in the second paragraph. It describes what people do — the full time and temperature as if starting from scratch — and marks it as a default rather than a recommendation, inside its own sentence. That is a source declining to endorse the workaround it is describing, which is exactly the distinction this site tries to keep.
Note also what it does not say. It does not say re-canned food is dangerous. It says nobody has done the work, so there is no number to give you, which is a statement about the research and not about your dinner.
And why the seal test will not settle this for you
Option 1. Press the middle of the lid with a finger or thumb. If the lid springs up when you release your finger, the lid is unsealed. Option 2. Tap the lid with the bottom of a teaspoon. If it makes a dull sound, the lid is not sealed… Option 3. Hold the jar at eye level and look across the lid. The lid should be concave (curved down slightly in the center).
USDA Complete Guide to Home Canning, 2015 revision, p. 1-25
The link above opens the document itself, so a printed page number leads somewhere. What this document is, and who maintains it.
Opened and read by this site on 2026-08-26.
Everyone in this situation runs the seal test, hopes for a good result, and takes it as a partial reprieve. It is worth being clear about what a good result there means.
All three of these tests are measurements of one thing: whether a vacuum formed inside the jar. They involve a finger, a spoon and an eye, and they read the position of a piece of metal.
A vacuum forms whenever hot contents cool inside a closed jar. It forms in a jar that was pressure canned on a current schedule, and it forms in a jar that was filled with hot food and closed with no processing at all — SDSU Extension notes that jars may seal by that method while the bacteria in them are not destroyed [F-10.2].
So the seal test cannot distinguish between the batch you meant to make and the batch you actually made. A good result tells you the closure worked. The question you came here with is about the heat, and no test you can run on a cool jar reaches it.
What people ask next
I water-bathed something low-acid. Can I put the jars in the pressure canner now?
There is no tested process for re-canning already-canned food, so there is no schedule anybody can give you for that [F-9.7]. If the jars are fresh out of the canner, my own answer is to treat the contents as cooked food: refrigerate and eat within a few days, or freeze. If they have been on a shelf, do not open them to check — see the disposal procedure on Botulism: what to actually do [F-11.8].
Everything sealed perfectly. Doesn't that count for something?
It counts as evidence that your jars, lids and rims did their job, which is real. It is not evidence about the process. Jars closed with no processing at all seal reliably [F-10.2], which is precisely why seal quality cannot be used as a proxy for anything else. There is more on this on how to tell a sealed jar from a jar with a lid on it.
It has been in the cupboard for two years and nobody has been ill.
That is genuinely reassuring about the jars that have already been eaten and tells you nothing about the ones still on the shelf. The four conditions C. botulinum needs are about the contents of a jar, not about how long it has stood [F-1.4], and toxin can be produced within days of growth starting rather than over years. A batch is not a single object with one outcome; each jar is its own event.
I feel stupid. How did I not know?
Because the pages that teach these methods are confident, well written, well photographed and rank above the Extension services that contradict them. Several of them are on sites that get most things right, which is worse, not better — a page is easier to trust when the rest of the site is good. Working out that something was wrong from the inside, without anyone telling you, is difficult, and you did it.
Somebody already ate some of it. What do I do?
That question leaves the kitchen. Read Botulism: what to actually do now rather than continuing here. The short form is that the illness is rare, the symptoms are specific and unusual, and if they appear it is an emergency rather than something to investigate further.
Read these yourself
NCHFP — Canning FAQ (re-canning, and other questions the guide does not cover)
nchfp.uga.edu
NCHFP — Identifying and handling spoiled canned food
nchfp.uga.edu
SDSU Extension — The 'why' behind unsafe canning practices
extension.sdstate.edu
Penn State Extension — Foods that are not safe to can
extension.psu.edu