Glue flaps that will not hold

A glue flap fails when the adhesive cannot wet the surface. Coating, laminating film, or a varnish on the flap is the usual reason.

Checks

1. See whether the flap was coated or filmed. Glue specified for bare board will sit on a coating.
2. Leave the flap free of ink and coating when the design allows it. A printed flap needs a glue made for that surface.
3. Check compression and open time. A glue that skins before the flap closes will not grab.
4. A flap that opens in a warm truck was often a marginal bond. Test cartons after they have cooled and after they have been warm.

Materials in the directory

Compare paperboard, coatings, folding-carton laminating films.