Can Liner Seal Types

What it is

Liners are made from tubes of film. The bottom is closed by a heat seal, and the way the film is folded before sealing gives the seal type. A star seal gathers the bottom into folds and seals them together, so there are no side gaps. A flat seal seals straight across a flat tube. A gusset seal has the sides tucked in (gussets) before sealing, which makes a bag that opens into a squarer shape but leaves layered corners at the seal.

How to identify

Open a liner and look at the bottom. A star seal has a single seal line with the film folded in several layers, and the bag opens into a round shape with no corners. A flat seal has a straight line across a single fold and opens with two pointed corners. A gusset seal shows folded sides and multi-layer corners at each end of the seal line.

Seal type comparison

Key points

• Star seal liners hold more because they fill the bottom of the can with no wasted corners.
• Gusset seal liners can leak at the folds when liquid sits at the bottom. Avoid them for kitchen and food waste.
• Flat seal liners are often sized by width, and the bunched corners can tear when filled. Size to the can perimeter. See the can liner sizing chart.
• Coreless rolls and interleaved rolls (each bag pulls the next) are packaging options, not seal types.
• Resin and thickness still matter. See can liner resins, LLDPE vs HDPE.

Common mistakes

• Using gusset seal liners for wet waste.
• Buying by can capacity only and getting a poor fit in square or slim-jim cans.
• Blaming resin strength for leaks that come from the seal type.
• Overfilling so the seal takes the full weight when lifted.

Governing standards: No consensus standard defines liner seal types. Can liner maker data and site testing.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.