6 Best Silicone Bungs For Airtight Storage For Home Canners

The difference between a successful batch of lacto-fermented kraut and a compost-bound failure often comes down to the integrity of a simple seal. Properly securing your ferments and preserved goods protects against oxygen infiltration, keeping unwanted molds at bay throughout the growing season. Choosing the right silicone bung ensures that every jar, jug, or carboy remains an airtight vault for the harvest.

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Brewer’s Best Bung: The Reliable All-Rounder

The Brewer’s Best bung is the standard-bearer for a reason. Its high-quality, food-grade silicone construction provides just enough flexibility to form a tight seal against glass, yet enough structural rigidity to hold an airlock firmly in place. It stands up to repeated sanitization cycles without cracking or losing its shape.

This option is the ideal workhorse for the hobby farmer who manages a rotating collection of half-gallon and gallon fermentation vessels. Because it fits the standard neck sizes found on most hobby-grade glass jugs, there is rarely a need to search for specialized hardware.

If you want a plug-and-play solution that simply works, this is the bung to purchase. It avoids the fuss of gimmicky designs and performs exactly as expected. Keep several on hand to streamline the workflow during peak harvest.

Fermtech Universal Bung: Best for Multiple Jars

The Fermtech Universal Bung is a masterclass in clever engineering. Its unique, stepped design allows a single stopper to fit several different vessel neck diameters, ranging from small jugs to larger carboys. This eliminates the need to maintain an oversized inventory of varied stopper sizes.

For the farmer with limited storage space and a diverse collection of glass containers, this versatility is a significant advantage. It ensures that an airtight seal can be achieved regardless of which jar is pulled from the shelf.

Despite its versatility, the stepped design can occasionally be harder to clean than a smooth-sided bung. If you maintain a strict sterilization routine, this minor maintenance trade-off is well worth the convenience. It is the go-to choice for those who value versatility above all else.

Better-Bottle Stopper: A Secure, Custom Fit

The Better-Bottle stopper is engineered specifically for those who prefer lightweight, specialized PET carboys. Unlike generic bungs, these stoppers are designed to seat perfectly within the unique mouth dimensions of Better-Bottle containers. They provide a deeper, more recessed fit that reduces the risk of accidental dislodgment during transport or heavy handling.

The material is non-porous and resists the absorption of odors, which is essential if the same equipment is used for different types of ferments or infused liquids. A lingering scent of last season’s garlic brine is the last thing anyone wants in a delicate vinegar.

If the goal is long-term stability and a secure, non-slip fit for specialized carboys, this stopper remains unmatched. While it lacks the universal fit of other options, its specialized design ensures peak performance in its intended role. Stick to this brand if the equipment matches; the seal is consistently superior.

Vintage Shop Solid Bungs: For Long-Term Aging

When it comes to long-term storage where no airlock is needed, solid bungs are essential. The Vintage Shop solid silicone bungs provide a completely airtight, leak-proof seal that is perfect for final aging or secondary storage. By removing the aperture for an airlock, you minimize the risk of evaporation and oxidation.

These bungs are particularly useful during the quiet winter months when ferments have settled and the focus shifts to preservation stability. The silicone is soft enough to press firmly into the neck but dense enough to remain undisturbed for months at a time.

These are not intended for active ferments that generate gas, as the lack of an airlock would lead to pressure buildup. However, for sealing finished cider or vinegars, they are excellent. Buy these specifically for the secondary stage of the process.

North Mountain #6.5 Bung: For Standard Carboys

The North Mountain #6.5 bung is a reliable, medium-sized stopper that fits the most common glass carboys used in home settings. It is crafted from premium, high-density silicone that resists the deformation often seen in cheaper, rubber alternatives.

This specific size is often the missing piece of the puzzle for many hobbyists struggling with leaky carboy seals. The fit is snug and precise, requiring very little effort to seat properly while providing maximum protection against contaminants.

If you own standard 3-gallon or 5-gallon glass carboys, this is the standard. It provides the security needed for extended fermentation periods without excessive bulk. It is a no-nonsense, highly effective component that belongs in every storage kit.

Home Brew Ohio #10 Bung: For Gallon Jug Lids

The Home Brew Ohio #10 bung is the oversized solution for wide-mouthed gallon jugs or specialized large-opening glass jars. It is designed to bridge the gap between standard carboy sizes and the wider openings that often frustrate those trying to find airtight closures for larger batches.

While larger bungs can sometimes feel cumbersome, the quality of this silicone ensures that it retains its elasticity over time. It creates a robust seal that holds steady even when the fermentation activity is vigorous.

Those dealing with large-batch vegetable ferments will find this size invaluable. It is a specific tool for a specific problem, and it solves the airtight issue for wide-mouth vessels perfectly. For those handling large, high-volume ferments, this should be the top priority.

How to Measure for a Perfect Bung Seal Every Time

Achieving a perfect seal begins with accurate measurement. Never rely on visual estimation, as a difference of only a few millimeters can determine whether a bung pops out under pressure or slips into the jar. Use a pair of calipers to measure the internal diameter of the vessel neck.

When selecting a bung, always aim for a fit where the middle portion of the stopper is compressed when inserted. If the bung goes in too easily, it is too small; if it requires extreme force, it is likely to pop out as air pressure builds within the vessel.

• Small (Sizes 00-3): Best for small fermentation test tubes or sample jars.
• Medium (Sizes 4-7): Ideal for standard half-gallon and gallon jugs.
• Large (Sizes 8-12): Necessary for wide-mouth carboys and large-capacity vessels.

Drilled vs. Solid Bungs: Which One Do You Need?

The choice between a drilled and a solid bung depends entirely on the stage of the canning or fermentation process. A drilled bung includes a hole to accommodate an airlock or a blow-off tube, which is essential for any fermentation that produces carbon dioxide. Without this outlet, the internal pressure will eventually breach the seal or shatter the container.

Solid bungs, by contrast, are used exclusively for storage after the active fermentation phase is complete. Once the liquid has stabilized and the pressure has subsided, switching to a solid bung prevents any airflow.

Consider the seasonal workflow. During the active harvest, keep a supply of drilled bungs ready for the constant flow of new batches. Transition to solid bungs as the pantry fills and fermentation reaches its final, quiet conclusion.

Cleaning and Sanitizing Your Silicone Bungs

Silicone is durable, but it can harbor microscopic residues if not cleaned thoroughly after every use. Start by soaking the bungs in warm, soapy water to break down any oils or sugars. Use a soft-bristled brush to reach inside the drilled holes, as these are the most common areas for mold or bacteria to hide.

After cleaning, move to a standard sanitizer like Star San. Silicone is porous enough that it can absorb odors, so avoid using harsh chemicals or abrasive scouring pads that might create small grooves. These grooves serve as breeding grounds for unwanted microbes in the future.

Once sanitized, allow the bungs to air dry completely on a clean rack. Storing them while still damp invites mildew growth, which can ruin a perfectly good batch of cider or kraut. Proper care and maintenance of your bungs will ensure they remain functional for years of harvest cycles.

Troubleshooting Common Bung Sealing Issues

A bung that repeatedly pops out of a container is usually a sign that it is either too small, or the jar neck is wet. Silicone relies on friction to maintain its seal, and a layer of liquid or sanitizer will act as a lubricant, causing the bung to slide out. Always wipe the inside of the jar neck completely dry before inserting the stopper.

If the bung refuses to stay seated even when dry, the vessel neck might have a slight manufacturing imperfection. In this case, wrapping a small amount of plumber’s Teflon tape around the bung can add the necessary diameter to achieve a snug fit. This is a practical, temporary fix that keeps the fermentation process moving without needing new equipment.

If you observe the liquid inside the airlock being sucked back into the jar, the seal is airtight, but the temperature is likely dropping too rapidly. This creates a vacuum effect that pulls the airlock contents inward. To prevent this, keep your fermentation vessels in an area with a consistent ambient temperature, away from drafty windows or heating vents.

The right silicone bung is a humble piece of gear, yet it remains the primary defense for the home canner’s seasonal efforts. By matching the correct size to the vessel and maintaining consistent hygiene, the risk of spoilage is kept to a minimum. Invest in quality silicone, maintain your seals properly, and the pantry will remain well-stocked throughout the winter.