PREPRESS GUIDE
Cut lines and crease lines on a packaging dieline.
A cut line separates material; a crease line prepares it to fold. They may share a drawing, but they describe different tooling operations and must remain distinct from each other and from printable artwork throughout design, export, and prepress.
Read each line by its production role
Cut paths form the perimeter, slots, holes, and windows. Crease paths identify folds without removing material. Perforations create a controlled tear by alternating cut and uncut segments, while partial cuts and kiss cuts depend on the material and finishing process.
Colour and dash patterns are visual conventions, not the manufacturing instruction by themselves. Keep each operation on a named layer or spot colour agreed with the converter, and never rely on a viewer's appearance as the only distinction.
A crease has width and direction
A screen drawing reduces a crease to a line, but production uses a rule and channel with real width. Board grade, caliper, grain or flute direction, coating, and fold angle affect the crease specification and the finished panel size.
This is why the structural model and the converter's allowance table matter. Moving a crease by a small amount can change a lid fit or make two panels collide even when the flat artwork still looks tidy.
Preflight before artwork approval
Lock the structural layer before placing final artwork. Extend background colour beyond cut edges by the printer's required bleed, keep critical text and barcodes inside the safe area, and rotate panel artwork according to the folded orientation rather than the flat page.
Before release, verify that cut paths are closed where required, crease paths do not extend into unrelated panels, duplicate lines are removed, spot colours are named correctly, and no production line is set to print as ordinary artwork. Confirm the exported file with the converter before tooling.
Inspect cut and crease paths on real templates
Open the 2D drawing and use the line legend before comparing the same structure in the 3D fold view.