Historically, steam vacuum capping has been the dominant solution for glass containers. While effective, it is energy-intensive, relatively slow and can result in closures that are difficult for consumers to open. In addition, it offers limited flexibility for modern high-speed production environments.
Production formulation further complicates matters. Substances with high oil or fat content, or those containing volatile compounds from spices such as pepper, nutmeg or clove, can migrate into the sealing area. This contamination interferes with seal integrity, increasing the risk of leakage or failure.
A shifting regulatory environment
Alongside these technical hurdles, regulatory expectations have become more stringent. Earlier approaches often deemed packaging compliant if no leakage occurred under standard conditions. Today, requirements are rigorous.
Under frameworks such as Commission Regulation( EU) No 10 / 2011, materials used in food contact applications, including sealing adhesives, must demonstrate sustainability across a wider range of conditions, including exposure to fatty substances and variable orientation during transport.
This has significant implications for induction sealing on glass. Not all adhesive systems historically used with liners are compatible with fatty or oil-based products, meaning previously accepted solutions may no longer meet compliance standards.
As a result, manufacturers must ensure that all sealing components – not just the container and closure- are validated for their intended application.
Refining induction sealing for glass
To address these challenges, induction heat sealing technology has been further developed for glass applications. At its core, the process remains the same: a foilbased liner is inserted into the cap and bonded to the container rim through electromagnetic induction.
The critical difference lies in the adhesive system. Glass requires a specialised bonding layer capable of overcoming inert, non-porous surfaces while maintaining performance in the presence of oils, fats and volatile compounds.
One example is Selig’ s GlassFuzeTM heat seal technology, designed specifically for glass containers. When combined with liner systems such DELTASEALTM, Uni-GardTM or Lift‘ n’ PeelTM, it provides a hermetic seal while meeting the requirements of EU food contact regulations.
The structure typically consists of an aluminium foil laminated with a heat-seal polymer. During induction sealing, the foil heats rapidly, activating the polymer layer to form a bond with the glass rim. This creates a secure seal without the need for steam-based processes.
Performance and user experiences
Beyond compliance, these systems also address longstanding usability concerns. Unlike traditional vacuum caps, induction-sealed glass closures can be engineered for easier opening while still delivering clear tamper evidence.
For example, two-piece liner systems can produce an audible indication upon first opening, while leaving a foil seal on the container and a secondary reseal liner inside the cap. This supports both product integrity and consumer confidence.
Equally important is visual presentation. Modern liner technologies are designed to leave a clean, residue-free finish, maintaining product aesthetics after opening, an increasingly important factor in premium and retail-driven categories.
Looking ahead
Plastics will continue to play a central role in packaging, particularly where weight, cost and flexibility are critical. However, glass is firmly re-establishing itself as a material of choice where sustainability perception and product differentiation are key.
Advances in induction sealing are helping to remove one of the material’ s historic limitations. By enabling reliable, compliant sealing across a broader range of product types, including those with challenging formulations, these technologies are making glass a more viable option for modern production lines.
As the industry gathers at Interpack the direction of travel is clear: innovation is no longer about adding complexity, but about refining existing processes to meet evolving expectations. In that context, the evolution of glass sealing is less a breakthrough moment than a necessary step forward.
Boxout: GlassFuzeTM in focus:
Selig’ s GlassFuzeTM technology forms part of its, DELTASEALTM liner system, engineered specifically for glass container applications. The liner incorporates a polymer layer laminated between foil and backing materials. During induction sealing, this layer bonds directly to the glass rim, creating a hermetic seal that remains intact even with high oil, fat or spice content products.
On opening, the foil remains on the container to provide tamper evidence, while the closure retains a secondary reseal liner. The result is a combination of product protection, regulatory compliance and improved consumer usability.
To find out more about GlassFuze and DELTASEAL, visit Selig at Interpack, Hall 7, Level 1, Stand B06
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