How To Vacuum Seal Glass Jars

Learning how to vacuum seal glass jars is a fantastic skill for any home preserver. It extends the shelf life of your dry goods, protects against pests, and helps you save money by buying in bulk. This guide will walk you through several reliable methods, from simple tools to specialized equipment.

You’ll find that the process is straightforward once you understand the core principles. We’ll cover everything from jar selection to storage tips, ensuring your food stays fresh and safe.

Vacuum sealing removes air from a jar, creating an airtight environment. This slows down oxidation and spoilage, keeping food like flour, nuts, coffee, and dehydrated meals fresher for much longer. It’s a key step in long-term food storage.

Why Vacuum Seal in Glass Jars?

Glass jars offer several advantages over plastic bags for vacuum sealing. They are reusable, environmentally friendly, and don’t leach chemicals. Glass also provides a perfect barrier against odors and moisture when sealed correctly. Your food’s flavor and texture remain intact.

Zero Waste: Jars can be used indefinately, reducing single-use plastic.
Better Protection: Glass is impermeable and keeps out smells better than plastic.
Visible Contents: You can easily see what’s inside and how much is left.
Stackable Storage: Uniform jars make organizing your pantry simple.

Essential Supplies You’ll Need

Gathering the right tools before you start is crucial for success. You don’t need everything listed here; it depends on the method you choose.

Glass Jars: Use jars with a smooth, flat rim (like Mason jars). Ensure they are free of chips or cracks.
Lids & Bands: New canning lids are best for a reliable seal. Bands should be rust-free.
Vacuum Sealer: A countertop machine with a jar-sealing attachment, or a handheld vacuum sealer.
Alternative Tools: A heat-based method might only require your jar, lid, and a hot water source.
Oxygen Absorbers: Small packets that chemically remove residual oxygen, often used in conjunction with vacuum sealing.

Preparing Your Jars and Food

Proper preparation is the foundation of a good seal. Rushing this step can lead to failure.

Clean Thoroughly: Wash jars, lids, and bands in hot, soapy water. Rinse well. Sterilizing by boiling for 10 minutes is recommended for long-term storage.
Check for Damage: Inspect the jar’s sealing rim for any nicks. A flawed rim will not seal.
Dry Completely: Jars and lids must be completely dry before adding dry goods to prevent clumping or mold.
Fill Correctly: Leave adequate headspace (about 1 inch from the rim) for the vacuum process to work effectively.

Choosing the Right Jar Size

Select a jar size that matches the amount of food you’re storing. It’s better to use several small jars than one large one. Once opened, the vacuum is broken on the entire contents. Smaller jars minimize exposure for the remaining food.

Method 1: Using a Vacuum Sealer with a Jar Attachment

This is the most effective and consistent method. Many popular vacuum sealer brands sell special lid attachments designed for Mason jar styles.

Place your dry food into a clean, dry Mason jar.
Wipe the jar’s rim clean to ensure no debris interferes.
Place a new, dry canning lid on the jar and screw on the band fingertip-tight (not overly tight).
Attach the appropriate hose from your vacuum sealer to the machine’s port.
Connect the other end of the hose to the jar sealer attachment.
Place the attachment firmly onto the center of the jar lid.
Turn on your vacuum sealer and activate the suction. You will see the lid pull down and hear a change in sound when the air is removed.
Turn off the sealer, remove the attachment, and your jar is sealed. The band can be left on or removed for storage.

Method 2: The Water Displacement Trick

This is a clever, low-tech method suitable for short-term storage or when you don’t have specialized equipment. It works best with fats like butter or grated cheese.

Fill your jar with the desired food, leaving about 1.5 inches of headspace.
Place the jar lid on top but do not screw the band on.
Slowly lower the jar into a pot of warm water. Ensure the water level is above the food but below the jar’s rim.
The water pressure will push air out. After 30-60 seconds, carefully screw the band on tightly while the jar is still submerged.
Remove the jar, dry it, and as it cools, a vacuum seal will form. This seal is not as strong as other methods.

Method 3: The Oven Heat Method

This technique uses heat to create a vacuum as the air inside the jar cools and contracts. Use extreme caution and only for completely dry goods.

Preheat your oven to 200°F (95°C).
Place your dry food in clean, dry jars. Do not use lids yet.
Set the open jars on a baking sheet and warm them in the oven for about 15-20 minutes. This heats the air inside.
Carefully remove one jar at a time. Quickly place a dry lid on top and screw the band on tightly.
As the jar cools on the counter, the air inside contracts, pulling the lid down and creating a vacuum. You should hear the familiar “ping” as it seals.

Important Safety Note for Heat Methods

Never use this method for moist foods, liquids, or anything that can melt or burn. The jars will be hot; always use oven mitts. Sudden temperature changes can cause glass to break, so avoid drafts.

Method 4: Using Oxygen Absorbers

While not a vacuum method per se, oxygen absorbers achieve a similar result and are often used with dry-packed jars. They are simple and require no machines.

Fill your jar with dry food, leaving about an inch of headspace.
Select the correct size oxygen absorber packet for your jar volume (e.g., a 100cc packet for a quart jar).
Drop the absorber into the jar on top of the food.
Immediately seal the jar with a tight-fitting lid. The absorber will begin working right away, scrubbing oxygen from the headspace.
Within a few hours, you should notice the lid has been pulled down, indicating a vacuum has formed.

Testing Your Seal and Proper Storage

Always verify that a proper seal has been achieved before storing your jars away.

The Button Test: For lids with a “safety button” center, press down. If it doesn’t pop, the seal is good. If it flexes up and down, the seal failed.
The Tap Test: Gently tap the lid with a spoon. A sealed lid makes a clear, high-pitched ring. A failed seal makes a dull, hollow sound.
The Lift Test: After removing the band, try to lift the jar by the lid only. A proper seal will hold the jar’s weight.

Store your vacuum-sealed jars in a cool, dark, and dry place. A basement pantry or cupboard away from the stove is ideal. Light and heat are the enemies of long-term food storage.

Troubleshooting Common Problems

If your seals are failing, one of these issues is likely the cause.

Lid Doesn’t Pull Down: The jar rim might be dirty or chipped. The lid could be defective or the band was screwed on too tightly before vacuuming, not allowing air to escape.
Seal Fails Over Time: This usually indicates a poor initial seal or the food was not completely dry, allowing internal moisture to compromise the vacuum.
Jar Breaks During Process: Using a cracked jar or subjecting a hot jar to a cold surface can cause breakage. Always inspect jars and handle with care during heat methods.
Food Loses Freshness Quickly: The storage location may be too warm or humid. Consider using oxygen absorbers in addition to vacuum sealing for very long-term storage.

What Foods Are Best for Vacuum Sealing in Jars?

This method is perfect for dry, shelf-stable foods. Here’s a list of ideal candidates:

Grains (rice, quinoa, oats)
Flours and meals
Dried beans and lentils
Pasta
Nuts and seeds
Dehydrated fruits and vegetables
Whole coffee beans or ground coffee
Spices and herbs
Powdered milk or drink mixes
Brown sugar (to keep it soft)

Foods to Avoid Vacuum Sealing in Jars

Do not vacuum seal moist foods, fresh produce, or soft cheeses in this manner unless you are using a dedicated canning process (like pressure canning for wet foods). It can create an anaerobic environment conducive to botulism growth. Stick to dry goods.

FAQs About Vacuum Sealing Jars

Can you vacuum seal any glass jar?

You can only vacuum seal jars with a perfectly flat, smooth rim designed for sealing. Standard Mason or canning jars are made for this. Jars from pasta sauce or pickles often have slightly curved rims that won’t form a reliable seal with a flat lid.

How long does vacuum-sealed food last in jars?

Shelf life varies by food. Most dry goods last 1-3 years or longer when properly vacuum-sealed and stored in ideal conditions. Compare this to a few months in their original packaging. Always label your jars with the contents and date.

Is it cheaper to vacuum seal in jars or bags?

Jars have a higher upfront cost but are reusable indefinately, making them cheaper over time. You avoid continually buying plastic bags, which saves money and reduces plastic waste. The initial investment in a jar sealer attachment is minimal.

Can you reuse the lids for vacuum sealing?

Canning lids are designed for a one-time seal during the actual canning process. For dry vacuum sealing, you can often reuse them a few times if the sealing compound is still soft and pliable. However, for the most reliable seal, new lids are recommended, especially for long-term storage.

Do you need to refrigerate vacuum-sealed jars?

For the dry goods discussed here, refrigeration is not necessary and can introduce moisture if the jars are brought in and out of the cold. Store them in a cool, dark pantry. Refrigeration is only needed for perishable foods, which generally shouldn’t be stored this way unless properly canned.

Final Tips for Success

Start with a simple batch like rice or nuts to practice. Label every jar clearly with a permanent marker. Include the contents and the date it was sealed. Rotate your stock by placing newly sealed jars at the back of the shelf. This ensures you use older food first, maintaining freshness across your pantry.

Mastering how to vacuum seal glass jars is a practical step towards a more organized and sustainable kitchen. With these methods, you can confidently preserve your food, reduce waste, and always have ingredients on hand. The process quickly becomes a simple part of your routine after a few tries.