Start with the Two Surfaces
Identify both materials, including printing, varnish, coating and surface treatment. Uncoated paper, varnished board and plastic film do not behave alike. Provide samples from actual production: a different paper supplier or film construction can change the bonding result.
Match the Application Method
Record whether the adhesive is applied by roller or nozzle, the line speed and the interval between application and assembly. Hot melt operating windows and setting behaviour vary by formulation. Follow the selected grade’s technical data sheet; raising temperature is not a universal remedy for weak adhesion.
Check the Finished Pack’s Use
Explain whether the product will encounter refrigeration, moisture or heat, and whether it is food packaging. Initial bond strength alone is insufficient: evaluate after storage and under intended use conditions. Review food-packaging documentation for the particular grade and complete packaging construction.
Define Success Before the Trial
Agree on clear criteria: closure integrity, bond appearance, stable running and adhesive consumption per accepted unit. Compare on the same materials and equipment, recording adjustments and results. This turns adhesive selection into a decision that can be explained and reviewed.