Why does the pocket bulge or the lock open in a presentation folder?

Identify when the fault first appears

If an empty pocket lies flat but opens after brochures are inserted, check capacity first. If it already bows before loading, inspect crease position, folding order and overlapping layers. A lock that releases only when the folder closes may be reacting to tension between the pocket and cover.

The same symptom can have several causes. Using a longer tab to restrain an overfilled pocket can make assembly harder or start a tear at the slot. Record the stage at which the distortion begins before revising the dieline.

The actual insert determines pocket capacity

Pocket geometry cannot be based on length and width alone. Combined sheet thickness, quantity variation, catalogues and business cards all change the required volume. A sample approved with a few sheets may behave differently from the complete proposal pack.

Load the intended contents. If the pocket mouth grips the papers, material gathers at the base or the cover springs open, review the volume allowed in the construction. Approval should reflect the loaded and closed folder, not only its flat appearance.

Integral and glued pockets need different solutions

An integral pocket folds from the folder body, so its base, side returns and lock share the folding resistance of one board. A small crease-position difference can create tension at the mouth or misalign the lock. A glued pocket adds part position, glue allowance and finished-surface bonding to the diagnosis.

Business-card slits are functional cuts, not decorative marks. Check the real card size, orientation and distance from the pocket crease. Extending a slit must not leave a weak strip of board beside it.

Review lamination, glue area and creasing together

Lamination changes folding stiffness and the surface presented to adhesive. A plain-board prototype may not represent spring-back or bonding in production. The converter must verify glue area and adhesive on the finished stock; making the die does not imply that the die maker applies lamination or adhesive.

A single crease can force an overly sharp turn through thick or overlapping layers. A paired crease may provide folding volume where the construction needs it, but it is not a default fix. Decide its geometry from the selected board and a loaded sample.

Grain direction changes pocket and cover spring-back

Folds running with and across grain do not offer the same resistance. An unfavourable pocket hinge or cover crease can spring back and keep pulling on the lock. Sheet layout should consider the direction of principal folds as well as material yield. Heavy creasing should not be used simply to overpower grain because it can introduce crushing or surface damage.

Approve the sample empty, loaded and closed

Use production board, finish and the planned pocket method. Open and close the folder several times, then leave it with the real insert and inspect the pocket profile again. Mark the approved sample with its insert set and stock.

• Does the empty pocket lie flat against the body?
• Can the real insert enter without forcing the mouth or base?
• Does the lock engage naturally and remain seated?
• Do the card slits retain the card without weakening nearby board?
• Is there lifting, a hard patch or layer build-up at the corners?
• Does the loaded, closed folder develop a pocket mark or body bulge?