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Are plastic containers, buckets and cups leak-proof?

Many of our plastic containers, buckets and cups are suitable for liquid products when the lid is correctly fitted. However, whether a container is sufficiently leak-proof for a specific application depends on the particular container-lid system, the filling product and the filling, storage and transport conditions.

Correct positioning of the lid is particularly important for reliable sealing. The sealing and snap-fit areas should be clean and dry when the container is closed. If liquid or product residues remain between the rim of the container and the lid, the seal may be impaired and the filling product may leak.

Particular attention is required with oils, fats and oil-containing products. Due to their flow characteristics, these products may penetrate even very small gaps. A container that is leak-proof when tested with water is therefore not automatically suitable for every other liquid product under all conditions.

External factors can also affect leak-tightness. These include temperature, internal pressure, mechanical loads, stacking pressure, movement during transport and changes in the filling product during storage and transport.

Where an application has particularly high requirements regarding leak-tightness, an additional seal may be useful or necessary depending on the packaging system. Whether foil sealing, induction sealing or another sealing method is possible depends on the specific container-lid system.

Important: Leak-tightness for liquids should not be confused with gas-tightness. Unless specifically stated otherwise for a particular product, our standard containers are not intended as gas-tight packaging or for packaging under modified atmosphere (MAP).

Particularly for liquid, oily, fatty or technically demanding filling products, we recommend testing the packaging under the actual conditions of the complete process chain before series use – from filling and closing through storage and transport to final use.

Leak-tightness of plastic containers – what should be considered?

Factor What should be considered? Recommendation
Container and lid Leak-tightness depends on the interaction between the specific container-lid system and the correct positioning of the lid. Use only the lid intended for the respective container and make sure it is completely closed.
Sealing area Liquid or product residues between the rim of the container and the lid can impair the seal. Keep the sealing and snap-fit areas clean and dry before closing.
Filling product Oils, fats and oil-containing products may penetrate even very small gaps due to their flow characteristics. Always test leak-tightness using the actual filling product intended for the application.
Temperature Changes in temperature can affect the filling product, internal pressure and the mechanical properties of the packaging. Wherever possible, carry out testing under the temperature conditions expected during actual use.
Storage and transport Stacking loads, pressure, vibrations, impacts or an unfavourable position of the container can increase the demands placed on the closure system. Include the complete storage and transport chain in the suitability assessment.
Leak testing Test methods and test conditions may vary depending on the manufacturer and packaging system. Do not automatically transfer a positive result obtained under specific test conditions to every filling product or application.
Additional sealing Depending on the container-lid system, an additional foil, induction or other seal may improve the leak-tightness of the packaging system. Where high leak-tightness is required, check which sealing method is intended and suitable for the specific packaging system.
Gas-tightness / MAP Leak-tightness for liquids does not automatically mean gas-tightness. Unless otherwise specified, standard containers are generally not intended for modified atmosphere packaging (MAP). For MAP or other applications requiring a gas barrier, use a packaging solution specifically designed for this purpose.

Practical recommendation

Leak-tightness should always be tested under the actual conditions of use. In particular, consider the filling product, filling temperature, closing process, storage period, storage temperature, transport and mechanical loads.

Particularly for liquid, oily or fatty filling products, we recommend carrying out a practical test using the actual filling product and the intended container-lid system before series use.