My Canning Jar Didn't Seal — Is It Safe?

If a jar has not sealed within 24 hours of processing, do not store it at room temperature. Bernardin publishes three endings for it. Two are below; the third is to freeze it in a proper freezer container, which is the one that suits a big batch. Discarding is always yours as well:

1. Refrigerate it and use within a few days.
2. Reprocess it immediately with a fresh SNAP lid, for the original recipe’s full time. Bernardin’s word is immediately — the 24 hours is when you check, not a deadline you have until.
3. Discard the contents.

Never put an unsealed jar in the pantry. Without a vacuum seal, spoilage rises sharply — and for low-acid foods so does botulism risk.

You did everything right. Boiled the canner. Wiped the rims. Lowered the jars carefully. Heard a few satisfying pings as they cooled overnight. Then this morning, one jar — sometimes more than one — has a button on top that’s still up. Or you press the centre and it pops back like a snap bracelet.

It is a critical question, because the answer depends on whether the food is high-acid or low-acid, whether you noticed within 24 hours, and what the contents look like.

As an Amazon Associate we earn from qualifying purchases. Some links on this site are affiliate links — they cost you nothing extra and help keep the site free. We do not test products; we report what Bernardin and Canadian health authorities publish. Affiliate disclosure.

How to tell a jar did NOT seal

After the jars have cooled undisturbed for 24 hours on a towel-lined counter, take the band off. Both of these checks find a failure; neither one clears a jar.

1. Press the centre button. If it pops in and out, or flexes at all, the jar did not seal. A button that is firmly down and rigid has no defect you can feel — which is not the same as a guarantee.
2. Lift the jar by the lid alone. If the lid lifts off, it didn’t seal. This is the check Bernardin publishes, and they state it in one direction only:

If a lid can be removed without the use of pressure, do not use the product.

There is no sound test. Bernardin’s home canning FAQ does not mention the sound at all, and neither does HealthLink BC or Québec — so tapping a lid cannot tell you a jar sealed, and cannot tell you it did not. What makes a jar shelf-stable is the processing itself: the right method, for the full time, for that food in that jar size.

You have 24 hours. Here’s the decision tree.

Leave the jars undisturbed for 24 hours, then check the seal. What follows is what to do if it has not sealed.

Option 1: Reprocess (immediately, once you find it unsealed)

Best path if the jar should be shelf-stable. Bernardin publishes this as one of three endings for a lid that has not sealed within 24 hours, and their instruction is to reprocess immediately rather than at some point inside a window.

1. Remove the band and lid.
2. Pour the contents back into a clean pot. Discard any contents that look spoiled — off smell, foam, mould, anything that isn’t right. Don’t try to save those.
3. If the product was packed hot originally, reheat the contents — that condition is Bernardin’s, and a raw-packed product does not get reheated.
4. Wipe the jar rim with a clean damp cloth. Check the sealing edge for tiny nicks or imperfections; if the glass is damaged, replace the jar. Pack into a clean, hot jar — and if the recipe’s processing time is under 10 minutes, sterilize the jar before filling it.
5. Apply a fresh SNAP lid (the old one cannot be reused — see our SNAP lids guide for why).
6. Apply a band fingertip-tight.
7. Process in the boiling water bath for the full original recipe time at your altitude. Don’t shortcut the time — this is a complete reprocessing, not a top-up.

Cool, check the seal, label, store.

Option 2: Refrigerate and use within a few days

Best path if you don’t have time to reprocess, or only have one or two unsealed jars from a big batch.

1. Wipe the jar rim clean.
2. Apply a band (the old lid is fine for the fridge — it’s not creating a vacuum, just keeping dust out).
3. Refrigerate immediately.
4. Use within a few days. That is Bernardin’s own figure for an unsealed jar, and it is the one this site follows. Smell works one way only: an off smell, mould or sliminess on opening means discard — but a normal smell is not a clearance. Go by the date, not by the sniff.

For low-acid foods (anything pressure-canned: beans, soups, meats, vegetables), take the short end of that few days rather than the long end. Low-acid + a failed seal + room temperature is the textbook setup for Clostridium botulinum, and no authority publishes a separate refrigerator window for it.

Option 3: Discard

Best path if:

• It’s been more than 24 hours since original processing.
• The contents look or smell off in any way.
• It’s a low-acid food (meat, beans, vegetables, soup) and you’re not 100% sure when it failed.
• You’d otherwise stress about it every time you opened the pantry.

The cost of discarding a single failed jar is a few dollars in ingredients. The cost of consuming a contaminated low-acid jar is potentially a hospital trip. The math is not close.

How to discard safely, following HealthLink BC’s steps: put the contents in a waterproof container, put that container in the garbage, do not feed it to pets or other animals, wash your hands with warm soapy water, and wash every utensil and surface it touched. Wash the jar in hot soapy water and reuse the jar; the SNAP lid is finished.

Corrected 18 September 2026. This page used to tell you to tip the contents into the toilet and flush. That is not HealthLink BC’s instruction, and this site retired the same line from how to tell if home-canned food has gone bad in August without reaching this page. Nothing you have already thrown out needs revisiting — what changed is where it goes, not the decision to discard it.

Why your jar didn’t seal — the seven common causes

In rough order of how often each shows up:

1. The SNAP lid was reused

The red sealing compound is single-use. Reusing a SNAP lid gives a low-percentage seal that may or may not hold. Buy fresh lids; the savings aren’t worth it. (Full SNAP-lid rules here.)

2. The jar rim had a chip or sticky residue

Run your finger around every rim before applying lids. A nick you can barely see is enough to let air through. Wipe the rim with a damp cloth before applying the lid; sticky jam residue is also a seal-killer.

3. Contents were too cold when packed (cold-pack into hot canner)

If you cold-packed (raw-pack) contents into jars and lowered them into already-boiling water, the contents heated too fast on the outside and the air inside didn’t have time to escape properly. Best practice: lower jars into a canner of simmering water, then bring to the boil. Or hot-pack the contents.

4. Wrong headspace

Each recipe specifies a headspace (typically 0.5 cm / ¼ inch for jams and jellies, 1 cm / ½ inch for pickles, tomatoes and fruit in syrup, and 2.5 cm / 1 inch for pressure-canned meats and stocks). Too little headspace and the contents siphon out during processing, leaving residue on the rim. Too much and the air can’t escape properly. Match the recipe.

Corrected 18 September 2026. This line used to end the list at “1 cm / ½ inch for everything else”, which is Bernardin’s figure for pickles, tomatoes and fruit in syrup and is wrong for the pressure-canned beans, meat and broth this page names throughout — their figure for meats and stocks is 2.5 cm / 1 inch. If you packed a pressure-canned meat or stock to 1 cm on the strength of that line, expect siphoning and check the seal; treat a jar that did not seal exactly as this page describes.

5. Siphoning during processing

If you see a film of food residue stuck to the lid or rim after processing, the contents siphoned out — usually because pressure changed too fast (you yanked the canner lid off mid-cool, or you added the jars to water that wasn’t hot enough). Cool the canner gradually; resist the urge to peek.

6. Bands applied too tight

Fingertip-tight only. If the bands are torqued down hard before processing, the trapped air can’t push past the lid edge to escape, and the seal forms badly — or the lid buckles. “Fingertip tight” = until you feel resistance, then a quarter-turn more. No more.

7. The lid wasn’t seated properly before processing

If you set the lid down crooked, or if a piece of food got stuck between the lid and the rim, the seal can’t form. Always centre the lid carefully before applying the band.

What does NOT cause a sealing failure

A few myths worth retiring:

• “I should have boiled the lids first.” Bernardin advises against preheating SNAP lids: the sealing compound performs better at room temperature. The plastisol seals just fine without it.
• “My altitude is too high.” Altitude affects processing time (for water-bath) or pressure (for pressure canning), not whether seals form. A jar processed for the correct time at your altitude band will seal.
• “The barometric pressure was bad that day.” Doesn’t matter at any normal Canadian weather. Atmospheric pressure differences during cooling are far larger than any storm-system variation.

When unsealed turns into a safety issue

For high-acid foods (jam, pickles, acidified tomatoes, fruit), the acid is what stands between the jar and Clostridium botulinum. Public Health Ontario puts its growth above pH 4.6, and a correctly acidified product sits below that. This is why high-acid and low-acid foods get different answers on this page.

That is not a reason to keep an unsealed jar, and it is not a reason to judge one by smell. An unsealed jar has been open to the air for an unknown length of time. Refrigerate it within the window above, or discard it. HealthLink BC states that contaminated home-canned food “may look and smell normal, making it hard to tell if it is poisoned” — so a jar with no off smell has told you nothing.

For low-acid foods (anything pressure-canned: beans, corn, peas, meat, broth, low-acid soups), an unsealed jar at room temperature is the textbook condition for Clostridium botulinum growth. The toxin is odourless, tasteless, and lethal. Visible signs are inconsistent — sometimes the lid bulges, sometimes the contents foam on opening, sometimes neither.

For any low-acid food that didn’t seal, do not store at room temperature. Refrigerate within hours of noticing or discard. See our botulism check guide for what to watch for on opened jars later.

Next steps

• Read the water-bath canning pillar for the broader method.
• See SNAP lids reuse — fresh lids are non-negotiable for reprocessing.
• Can you can with cracked jars? — the related jar-condition question.
• For low-acid foods: pressure canning pillar covers the method that’s actually safe.

If you have already eaten from a jar you now doubt, and anyone develops double or blurred vision, drooping eyelids, slurred speech, difficulty swallowing or muscle weakness — call 911 or go to an emergency department immediately. Botulism antitoxin works best given early. Do not wait to see whether it passes.