Vacuum Sealing Mason Jars: Step-by-Step Guide

Collect all necessary equipment before starting: a vacuum sealer with an accessory port and compatible hose, such as the FoodSaver FM2100 or VS100 Compact, a mason jar lid attachment kit specifically designed for your sealer model, clean standard canning jars with matching lids and rings, and the food items you intend to preserve.

Thoroughly clean and completely dry your mason jars, lids, and rings. Any residual moisture on the jar rim or lid surface can compromise the seal and lead to spoilage. Inspect jars for any chips, cracks, or warping on the rim, as even minor imperfections can prevent a vacuum-tight seal.

Verify that your mason jar lid attachment kit is compatible with your specific vacuum sealer model. Most FoodSaver models use a standardized hose and attachment interface, but third-party or older sealer models may require specific adapters. Refer to your sealer's manual or the attachment kit's product listing to confirm compatibility, as an improper fit will result in air leaks and failed seals.

Fill the jar with your chosen food, leaving at least one inch of headspace so the food stays clear of the flat lid and the lid's sealing compound can seat cleanly on the rim. The vacuum presses that compound onto the rim as the pump draws the air down, so a clear rim is what the pull needs. Dry goods like beans, rice, or pasta can come close to the one inch line, never past it.

Place a new, unused flat lid on the mouth of the jar and screw the metal ring on just finger-tight. The jar attachment seats over the lid and pulls air from beneath it, so the lid needs to sit loose enough to flex down as the vacuum forms; an overtightened ring holds the lid up and kills the pull.

Never attempt to vacuum seal liquids or moist foods directly in a mason jar using an edge vacuum sealer without first freezing them solid. The vacuum pressure can draw liquid into the hose, potentially damaging the pump and causing the seal to fail. For soups, stews, or marinades, freeze the contents in the jar until completely solid before proceeding with the sealing process.

Locate the accessory port on your vacuum sealer. On models like the FoodSaver FM2100, this is typically a small, round port on the front or side of the unit, often labeled with a hose or container icon. Ensure the sealer is powered on and in standby mode.

Inspect the hose for any signs of damage, kinks, or blockages before connecting it to the jar attachment. Over time, food debris, dust, or moisture can accumulate inside the hose, reducing suction efficiency. If the hose is clogged, disconnect it from the sealer and blow through it or rinse it with warm water (if compatible) and allow it to dry completely before use.

Connect the other end of the hose to the jar lid attachment. The attachment is a domed seat that fits over the jar's flat lid with a gasket at its base: the pump draws air from beneath the lid through that seat, and nothing pierces the lid at all. Push the connection on until it feels firm, with no gap where air could sneak in.

Take the attachment and press it straight down over the flat lid until its gasket seats all the way around. Even pressure all around is what makes the seat airtight, and the attachment should sit flat without wobbling, because any tilt lets air leak past the gasket and the jar never pulls a vacuum.

Check the entire setup for security. Gently tug on the hose to confirm it is firmly connected to both the sealer's port and the lid attachment. Ensure the hose is not bent or pinched between the jar and the sealer, as this can restrict airflow and prevent a full vacuum.

Position the filled, unsealed jar on a stable surface near the vacuum sealer, making sure the hose is long enough to reach without stretching or straining the connections. The lid takes its seat during the pull, so keep the jar where nothing can knock it over mid-cycle.

Select the accessory or jar setting on your vacuum sealer's control panel; for machines without a dedicated jar mode, the 'Dry' or 'Normal' setting drives the same accessory pump. The cycle applies vacuum only, with no heat anywhere in the process: the pump draws the air out, the lid's sealing compound presses onto the rim, and the flat lid domes down at its center as the pull takes hold.

Press the 'Vacuum and Seal' button or the designated start button to initiate the sealing cycle. You will hear the vacuum pump activate, and you may see the jar lid being pulled downward slightly as air is removed from the jar. This visual confirmation is a good sign that the vacuum is working correctly.

Listen for the sealer's beep or indicator light, which signals that the cycle is complete. The machine finishes the jar once the vacuum is achieved: the seated lid is the seal itself. Do not interrupt the cycle or attempt to disconnect the hose while the pump is running, as this can cause the seal to fail or damage the sealer's internal components.

Once the cycle is complete, carefully disconnect the hose from the lid attachment by pressing the release collar on the hose or pulling it straight out. Then, remove the lid attachment from the jar lid. The flat lid should now be tightly sealed to the jar, with no give when pressed in the center.

Remove the metal screw ring from the jar. The vacuum seal holds the flat lid in place, so the ring is no longer necessary and can be removed for storage. This also allows you to inspect the seal more easily. Label the jar with its contents and the date of sealing using a waterproof marker or label.

Store the sealed jars in a cool, dark place such as a pantry, cupboard, or cellar. Avoid storing them in direct sunlight or near heat sources, as temperature fluctuations can degrade the seal over time. Properly sealed dry goods can remain fresh for many months or even years, significantly extending their shelf life compared to storage in non-sealed containers.