December 30, 2026
An induction seal is a foil liner bonded to the bottle's mouth using electromagnetic induction heat after the cap is applied, fusing a thin aluminum-and-polymer liner to the container rim. It's distinct from a simple wad or pulp liner inside the cap, which provides cushioning but no seal integrity or tamper evidence on its own.
Beyond tamper evidence, an induction seal provides a genuine moisture and oxygen barrier between capping and first use, which matters for supplements with moisture-sensitive actives, probiotics, certain vitamins, powdered blends, that can degrade or clump if exposed to ambient humidity during warehousing and retail shelf time before the consumer ever opens the bottle. It also prevents leakage during shipping for liquid and softgel products where a loose-fitting cap alone isn't a reliable seal.
Induction sealing equipment has become inexpensive enough, and retailer tamper-evidence expectations common enough, that skipping it now reads as a cut corner rather than a cost-saving choice. The per-unit cost of an induction liner is small relative to the retail rejection or return risk of shipping product without one, particularly for anything ingestible.
Induction sealing requires a compatible neck finish and cap liner combination, not every bottle and closure pairing is induction-seal-ready out of the box, and retrofitting it onto an existing program sometimes means confirming or adjusting the neck finish rather than just adding a liner. Confirm induction-seal compatibility at the sourcing stage if it's a requirement, not after bottles and caps are already tooled separately.
We build induction-seal-compatible neck finishes into supplement bottle programs as a standard specification, not an add-on decision made late in the process. For the broader tamper-evidence picture, see Tamper-Evident Packaging for Supplements.
See our plastic closures and caps capabilities and plastic bottle options, or request a quote.