Materials4 min read

A lined closure seals by compressing a separate disc against the neck land. A linerless closure seals with a moulded feature — a cone, a plug or an olive — that contacts the neck directly. Both work. They fail differently, which is what makes the choice worth thinking about.

Where linerless wins

One material, one part, no assembly step. Recycling is simpler, unit cost is lower, and there is no liner to fall out or be left out. Linerless designs also handle repeated opening well, because the sealing feature is moulded into the part and returns to shape.

Where a liner is still necessary

Aggressive solvents, long storage, hot filling and barrier requirements usually point to a liner. Induction liners add something a moulded feature cannot replicate: a visible, sealed membrane that shows whether the pack has been entered.

The decision usually turns on the neck

Linerless sealing demands tighter control of the neck land, because the closure has nothing soft to compensate with. If the container comes from a supplier whose tolerances are loose, a liner absorbs that variation. If the neck is well controlled, linerless is the cleaner engineering answer.

Test both, briefly

The reliable way to choose is a short parallel trial: same product, same capper, both systems, then leak and torque testing after conditioning. It costs a few days and settles an argument that otherwise runs for months.