How do you handle curled corners and bubbling? Differences in moisture content between the facing paper and the greyboard, along with the contraction of drying glue, can cause corner curling; solutions include controlling environmental humidity (refer to the article on board moisture content) and adjusting glue application and pressing parameters. When troubleshooting curled corners, check the humidity first before adjusting the process.
How long should the pressing last? Laminated boards require pressing to set their shape; pressing duration and pressure affect flatness, so large-area laminations require sufficient pressing time. To evaluate the result, let the board sit for a few days to see if it remains flat.
Paper lamination is the “face” of a rigid box: ensure even glue application, complete air removal, and sufficient pressure—mastering these three steps ensures a mirror-smooth box surface.
How do you control the glue? Apply glue evenly and in moderation; too much causes bubbling, while too little results in poor adhesion. Match the glue’s open time (drying/tack time) to the production pace. The standard for glue control is “secure adhesion without bubbling.”
How do air bubbles form? Bubbles occur when glue is uneven or air isn’t fully expelled during lamination, trapping air between the facing paper and the greyboard; both excessive and insufficient glue can cause this. When investigating bubble causes, start by checking the glue application rate.
Lamination (bonding facing paper to greyboard) defines the box’s appearance; a single bubble or curled corner can ruin the entire look. While bubble issues may seem minor, the cost of rework is high. This article clearly explains how to control bubbles and flatness during lamination, making it easy for custom rigid box clients to learn the process.
How do you expel air? Air must be removed after lamination: use a squeegee to push bubbles from the center outward, and ensure the pressure rollers on automatic laminating machines are correctly calibrated. The goal of air removal is to ensure no air remains trapped at the edges or corners.
