Compliance Clauses That Move Certificate Risk onto the Supplier
Moving certificate risk onto suppliers requires contract clauses that link claim validity to invoice codes, batch migration reports, and full indemnity for border holds.
Cut-Edge Exposure Migration
Penetration Mechanics
Fluid penetration through unsealed edges is a primary vulnerability of polymer-coated paperboards used in liquid packaging. The phenomenon of cut-edge exposure migration occurs when liquid is drawn into the exposed cellulose core by capillary action along the open perimeter of the carton. This absorption can weaken the structural strength of the board and cause the package to soften or fail.
The rate of this migration depends on the sizing agents added to the pulp and the viscosity of the liquid.
Barrier Compromise
Contact between the package contents and the unsealed paperboard edge can lead to chemical interaction or off-flavors in sensitive food products. Sizing treatments are applied during the papermaking process to make the fibres hydrophobic and slow down this lateral absorption. When these treatments are insufficient, the liquid penetrates deep into the board matrix and undermines the adhesion of the polymer barrier.
This process can cause the protective plastic layer to peel away from the paperboard substrate.
Testing Protocol
Laboratory assessments of edge wick resistance measure the weight gain of a sample after exposure to test liquids for specific durations. These procedures help converters select the appropriate sizing levels and edge-sealing techniques for specific packaging applications. This evaluation ensures that liquid cartons maintain their stiffness throughout their shelf life.