The short answer: vacuum sealing a mason jar is not canning. Canning heats a filled jar in a boiling water canner or a pressure canner for a tested length of time, and that heat is what lets properly canned food sit on a shelf. Vacuum sealing uses no heat. It only pulls the air out of the jar. That keeps food that is already dry fresher, and it helps food that is going into the refrigerator or freezer anyway, but it does not make soup, sauce, meat, or other moist food safe at room temperature. "Dry canning," heating jars of dry food in an oven, is something else again, and extension services say it is not a safe or recommended method.
We sell vacuum sealers. Read this knowing that. Where this page makes a food safety or storage claim, it links to the extension service or national center that made it.
Is vacuum sealing mason jars the same as canning?
No. They are two different processes that happen to use the same jar.
Canning is heat processing. A filled jar goes into a boiling water canner or a pressure canner for the time a tested recipe calls for. The heat destroys the organisms that spoil food or make people sick, and the lid seals as the jar cools. Low-acid foods such as vegetables, meat, and soup need a pressure canner. The National Center for Home Food Preservation says the bacterium that causes botulism is destroyed in low-acid foods when they are processed at the correct time and pressure in a pressure canner, and that using a boiling water canner for those foods poses a real risk of botulism.
Vacuum sealing is air removal. A machine pulls the air out of the jar at room temperature, and outside air pressure holds the lid down. No heat is involved, so nothing in the food is destroyed. University of Minnesota Extension says it plainly: mason jar vacuum sealers cannot be used to preserve foods that would otherwise be canned and processed with a boiling water bath, atmospheric steam canning, or pressure canning. Oregon State University Extension says vacuum packaging is not a substitution for the heat processing of home-canned foods.
There is one more reason to keep moist food cold after sealing. Oregon State notes that the bacteria that cause botulism grow at room temperature in low-acid, moist foods when the package lacks oxygen, and a vacuum sealed jar lacks oxygen. That is why a sealed jar of soup belongs in the refrigerator or freezer.
| Canning | Vacuum sealing a mason jar | |
|---|---|---|
| What it is | Heat processing a filled jar in a boiling water canner or pressure canner, for a tested time | Removing air from a jar at room temperature, so outside air pressure holds the lid down |
| Heat | Yes. The heat does the preserving. | None |
| Effect on spoilage organisms | A tested process destroys them | None. It removes air only. |
| Moist, low-acid food (soup, meat, vegetables) | Pressure canner and a tested recipe | Refrigerator or freezer after sealing, the same as before |
| Room temperature storage | Yes, for food canned with a tested recipe | Only for food that is already dry |
| Lids | Two-piece canning lids. Follow the lid maker's instructions. | Standard two-piece canning lids. Follow the lid maker's instructions on reuse. |
| Equipment | A canner, jars, lids, and a tested recipe | A vacuum sealer and a way to hold the jar: a chamber, a canister, or a jar attachment |
| Best for | Food you want to keep on a shelf, made from a tested recipe | Dry goods, freeze-dried and dehydrated food, and food going into the refrigerator or freezer anyway |
What is dry canning, and is it safe?
Dry canning is a name for two different home methods, and extension services advise against both. Penn State Extension describes them:
- Oven "canning" of dry food. Flour, dry beans, nuts, or similar foods go into mason jars, and the jars are heated in an oven set around 200°F until the lids seal.
- Pressure canning vegetables with no liquid. Vegetables go into jars without the liquid the tested recipe calls for.
Is it safe? No. Here is what the sources say:
- Penn State Extension: neither method is recommended for home food preservation. The seal an oven forms "is not a true vacuum seal as achieved during processing in a water bath or pressure canner," and the method "is not research-tested and can result in spoiled food or potential illness if consumed." Penn State adds that nuts and grains may go rancid faster, because heating increases oxidation.
- National Center for Home Food Preservation: processing jars in conventional ovens is not recommended because it does not prevent all risks of spoilage, and heating dry foods in canning jars in an oven "is also not a recommended science-based method of storing dry foods."
- University of Illinois Extension: this practice is unsafe. "Currently, there are no safe recipes for canning dry ingredients in the oven," and mason jars "are also not designed to be heated in an oven, which increases the risk of the jar shattering."
You will also see people call vacuum sealing a jar of rice "dry canning." That name is misleading. Vacuum sealing is not canning of any kind. It takes the air out of a jar of food that is already dry. It adds no heat and makes no claim to preserve anything that was not dry to begin with.
What can you vacuum seal in mason jars?
The rule is simple: where a food lived before you sealed it is where it lives after. Oregon State Extension puts it in one line: "Food that needs to be refrigerated without vacuum packing still needs to be refrigerated!"
Pantry shelf: food that is already dry
- Dried beans, lentils, and peas
- Rice, grains, oats, and pasta
- Flour, sugar, and baking staples
- Coffee beans, loose tea, and dried spices and herbs
- Dried or roasted nuts and seeds
- Freeze-dried and dehydrated fruit, vegetables, and meals
University of Minnesota Extension lists dried herbs, spices, fruits and vegetables, dry cereals, grains and legumes, and dried or roasted nuts and seeds as foods suited to vacuum sealed jars. Oregon State Extension says vacuum sealers may extend the storage times of dried foods, as well as refrigerated and frozen ones. For freeze-dried food, Penn State Extension says to put an oxygen absorber in the jar or remove the air using a vacuum sealer. See how to store freeze-dried food.
Refrigerator or freezer: food that was going there anyway
- Soup, stock, and broth
- Sauces and spreads
- Leftovers and meal prep
- Blanched vegetables for the freezer
These seal well and keep their quality better in the cold. University of Minnesota Extension says cooked, homemade foods like these "are not shelf-stable and must be refrigerated." See how to vacuum seal soup and liquids.
Not a job for vacuum sealing
- Keeping soup, sauce, vegetables, meat, or dairy on a shelf. That takes a tested canning process, or the refrigerator or freezer.
- Oven or "dry" canning of any food
See foods you should not vacuum seal, and what to do instead.
Where to keep sealed jars
Utah State University Extension says dried foods that pick up moisture from the storage area can grow molds and bacteria, that the best storage temperature is cool to moderate, about 40 to 70 degrees F, and that direct sunlight speeds the deterioration of both food and packaging. Glass lets light in, so keep jars in a closed pantry or cupboard. The National Center for Home Food Preservation suggests packing dried food in amounts you will use at one time, because each opening lets in air and moisture. Label every jar with the food and the date you sealed it.
Which jars work?
Standard mason jars made for home canning, with standard two-piece lids: a flat lid and a ring. Regular mouth and wide mouth both work. We recommend Ball jars.
- Check every jar for chips and cracks first. Run a finger around the rim and look for hairline cracks in the glass. A flawed jar can break under vacuum. Any glass jar can break, so skip one you are unsure of.
- Use clean, flat lids with no dents. Whether a used canning lid can be used again is a question for the lid maker. Follow the instructions on the box.
- Leave room at the top. Do not fill to the brim, especially with powders or liquids, and wipe the rim clean before sealing.
- Match the jar to the tool. In the JARMAX, pint and quart jars stand upright, and half pints stack on the stainless wire shelf that comes in the box. In the AVC400 canister set, the largest canister fits a wide-mouth quart jar. A regular-mouth quart jar may be slightly too tall for it. The jar attachment hood fits regular and wide mouth jars.
- Never lay a jar on its side to make it fit. Two verified buyers of our USV32, a chamber sealer designed around pouches, broke jars sealing them in that machine. A jar is made to stand on its base.
If a jar breaks: throw away the jar and the food in it, since glass can end up in the food. Then clean the chamber or canister carefully before you use it again.
How to vacuum seal mason jars with Avid Armor
There are three ways, depending on what you own and how many jars you seal. All three are for food that is already dry, or food that is going into the refrigerator or freezer.
Method 1: inside the JARMAX chamber, several jars at once
A chamber vacuum sealer does not pull air through a hose. It pumps the air out of the whole chamber with the jars inside. The air in each jar escapes past its loose lid at the same time. When the cycle ends, air rushes back into the chamber but not into the jars, and that outside pressure pushes every lid down.
- Check each jar for chips and cracks. Fill it, leave room at the top, and wipe the rim clean.
- Put the flat lid and the ring on. Leave the ring loose so the air can escape.
- Stand the jars upright in the chamber: up to four quart jars or six pint jars. Make sure nothing touches the machine's lid when it closes.
- Close the lid, set vacuum time to 25 seconds, and press Vac and Seal.
- When air returns to the chamber, lift the jars out.
- Press the center of each lid. A sealed lid is pulled down and does not flex. Tighten the rings, then label and date the jars.
The JARMAX is the chamber vacuum sealer we designed for this. The chamber is 12 x 11 x 8.5 inches, deep enough for quart jars to stand, with no hose and no special caps. Take the jars out and it is still a full chamber sealer, with a 10.5 inch seal bar for pouches up to 10 x 13 inches and Mylar up to 7 mil. It is $547, down from $699.
Method 2: inside the AVC400 canister set, one jar at a time
If you already own a vacuum sealer with an accessory port, the Avid Armor 3-Piece Food Vacuum Canister Set (AVC400) can seal a jar inside its largest canister, which holds 2 liters.
- Check the jar for chips and cracks, fill it, and wipe the rim.
- Put the lid on the jar and screw the ring on loosely.
- Set the jar inside the largest canister. A wide-mouth quart jar fits. A regular-mouth quart may be slightly too tall.
- Put the lid on the canister and turn the dial to SEAL.
- Connect the accessory hose from the canister lid to your sealer's accessory port, and run the accessory or canister function.
- When it finishes, disconnect the hose and turn the dial to OPEN.
- Take the jar out, press the lid to check the seal, and tighten the ring.
More on the set in maximizing kitchen storage with the 3-piece canister set.
Method 3: with the jar attachment hood, one jar at a time
The Avid Armor Jar Attachment Hood sits over the jar lid and connects to your sealer's accessory port by hose. It fits regular and wide mouth jars.
- Check the jar, fill it, and wipe the rim. Set the flat lid on. Leave the ring off.
- Place the hood over the lid so it sits flat on the jar.
- Connect the hose from the hood to the accessory port and run the accessory function.
- Remove the hose and the hood, check the seal, and screw the ring on.
For more detail on each method, see how to vacuum seal mason jars, step by step.
Chamber sealer vs canister vs jar attachment: which should you use?
It comes down to how many jars you seal at a time.
| JARMAX chamber sealer | AVC400 canister set | Jar attachment hood | |
|---|---|---|---|
| Jars per cycle | Up to 4 quart jars or 6 pint jars | 1 | 1 |
| Jar sizes | Pint and quart standing upright, half pints on the wire shelf | Largest canister fits a wide-mouth quart. Regular-mouth quart may be too tall. | Regular and wide mouth |
| Ring while sealing | On, loose | On, loose | Off |
| Hose | None | Yes | Yes |
| What else you need | Nothing. It is the sealer. | A vacuum sealer with an accessory port | A vacuum sealer with an accessory port |
| Also seals pouches and Mylar | Yes. 10.5 inch seal bar, Mylar up to 7 mil | No | No |
| Best for | A shelf of jars: freeze-dryer runs, bulk pantry days, broth by the pot for the freezer | An occasional jar, plus canister storage | A jar or two now and then |
- A jar or two now and then: use the jar attachment hood or the canister set with the sealer you already own. You do not need a new machine.
- Mostly pouches, a jar once in a while: a chamber sealer designed around pouches is the better buy. Compare the options in the best vacuum sealer for mason jars.
- Jars by the dozen: the JARMAX. Four quarts or six pints per cycle means a dozen pint jars take two cycles instead of twelve.
See the JARMAX and which jars fit or go straight to the JARMAX product page
Questions people ask
Is vacuum sealing a mason jar the same as canning?
No. Canning heats a filled jar in a boiling water canner or a pressure canner for a tested length of time, and that heat is what lets properly canned food sit on a shelf. Vacuum sealing only removes air at room temperature. University of Minnesota Extension says vacuum sealing a jar does not result in the same shelf-stable canned food that canning and processing provide.
Is dry canning safe?
No. Extension services do not recommend it. Penn State Extension says neither version of dry canning is a recommended method of home food preservation. The National Center for Home Food Preservation calls heating dry foods in jars in an oven not a recommended science-based method, and University of Illinois Extension calls the practice unsafe.
Is vacuum sealing mason jars the same as dry canning?
No. Dry canning means heating jars of food in an oven, or pressure canning vegetables with no liquid, and extension services advise against both. Vacuum sealing uses no heat at all. It removes air from a jar of food that is already dry, or from food that is going into the refrigerator or freezer anyway. Calling it dry canning is misleading, because it is not canning of any kind.
Does vacuum sealing a jar make food safe to keep at room temperature?
Only if the food was already dry. Vacuum sealing does not change what a food needs. Oregon State University Extension says vacuum packing is not a substitute for refrigerating or freezing food that would otherwise require it. Soup, broth, sauce, meat, dairy, and most cooked or fresh food still go in the refrigerator or freezer after sealing.
Can you vacuum seal soup or broth in a mason jar?
Yes, for the refrigerator or freezer. A jar stands upright, so a chamber vacuum sealer can take the air out without pulling liquid across the opening. The soup is still perishable after sealing. Leave room at the top of the jar, and keep it cold.
Do you need special lids to vacuum seal mason jars?
No. Standard two-piece canning lids work, in regular or wide mouth. The JARMAX seals jars with their own two-piece lids, with no special caps and no attachment. Use flat lids that are clean and free of dents. Whether a used lid can be used again is a question for the lid maker, so follow the instructions on the box.
Can a mason jar break in a vacuum sealer?
Yes, it can. Glass is still glass. Check every jar for chips and hairline cracks before you seal it, stand it upright, and leave the ring loose. Never lay a jar on its side to make it fit in a shallow chamber. Two verified buyers of our USV32, a chamber sealer designed around pouches, broke jars that way. If a jar breaks, throw away the jar and the food in it and clean the chamber carefully.
How long does food last in a vacuum sealed mason jar?
No food safety authority gives one number for every food, so we do not either. It depends on the food, how dry it is, and where you keep it. For dried foods, the National Center for Home Food Preservation publishes storage guidance by type of food. Perishable food does not gain room temperature life from sealing. It still needs the refrigerator or freezer.
Do you need oxygen absorbers if you vacuum seal mason jars?
Not always. For freeze-dried food in glass jars, Penn State Extension says to put an oxygen absorber in the jar or remove the air using a vacuum sealer. Some people use both for fatty foods. Our guide to oxygen absorbers and vacuum sealing covers when each one makes sense.
Can any chamber vacuum sealer seal mason jars?
Only jars that stand upright under the lid. Many chamber sealers are designed around pouches and are short inside. The USV32 chamber is 3.5 inches tall, too short for a pint or quart jar to stand. The JARMAX chamber is 12 x 11 x 8.5 inches, so four quart jars or six pint jars stand upright in one cycle.
Keep reading
- The JARMAX: a chamber vacuum sealer for mason jars, six pints a cycle
- How to vacuum seal mason jars: 3 methods, step by step
- The best vacuum sealer for mason jars
- How to store freeze-dried food: mason jars, Mylar, and oxygen absorbers
- Do you need oxygen absorbers if you vacuum seal?
- Mylar bags vs mason jars for freeze-dried food
- How to vacuum seal soup and liquids
- Foods you should not vacuum seal, and what to do instead
Sources
- University of Minnesota Extension: Vacuum sealing mason jars, are they safe for my cottage foods? (vacuum sealing is not canning; which foods suit sealed jars; cooked foods must be refrigerated)
- National Center for Home Food Preservation: For Safety's Sake (pressure canning for low-acid foods; botulism)
- National Center for Home Food Preservation: Equipment and Methods Not Recommended (oven processing and dry canning)
- National Center for Home Food Preservation: Packaging and Storing Dried Foods (containers, portion size, storage by food type)
- Penn State Extension: "Dry Canning" is Not Recommended
- Penn State Extension: Let's Preserve, Freeze-Drying (oxygen absorber or vacuum sealer for jars)
- University of Illinois Extension: Is canning flour safe?
- Oregon State University Extension: Should I vacuum package food at home? (not a substitute for heat processing or refrigeration; botulism risk in moist, low-acid food)
- Utah State University Extension: Food Storage Conditions (moisture, temperature, light)
Updated September 30, 2026. Avid Armor is designed and supported in Lenexa, Kansas.
