How to Prepare Artwork for Corrugated
Corrugated behaves differently from paper, and almost every print problem we see traces back to one of four things below.
Design inside the panels, never across them
Your dieline is not your artwork. A mailer box is cut, creased and folded from a single flat blank, and anything that crosses a score line will not register across it. Ask for the dieline first and place your design inside the panels. Design across a crease and the artwork visibly shifts when the box folds.
Check the grain direction before you place anything
Corrugated has a grain, created when the flutes were formed in one direction. Design elements have an appearance that depends on which way they sit relative to that grain — lines running across the grain read differently from lines running with it.
The practical rule, and the reason this matters commercially: ink
printed across the grain is more likely to crack, scuff and delaminate because the liner flexes perpendicular to the flutes. A large flood-printed area running the wrong way relative to the grain will show stress marks along the creases within weeks. Your dieline will show the grain — orient your type, your key graphics and any flood coverage with it.
Build in 3 mm bleed and check ink coverage
Standard bleed is 3 mm on every edge, on top of the manufacturer's trim allowance. Ink coverage above roughly 30% of the surface moves the box into a different price tier and, more importantly, affects recyclability — heavily flooded board is harder to repulp. If you need a full-bleed dark panel, ask what it does to the recyclability before approving it.
Use vector artwork, and check your smallest text
AI, EPS or PDF with vector shapes. Corrugated flutes create a visible texture that softens fine detail, so minimum text size is larger than on flat paper. Below about 6 pt, the flute texture interferes and the text reads as a grey smudge. Convert text to outlines, embed or outline your fonts, and keep a live-text version of the file for revisions.
Plan for where the product is actually seen
On a REFT mailer, the visible surfaces are the lid top, the front panel and the two side wings. The back panel is often covered by the shipping label. Put your strongest brand work where the label will not land, and leave a clear, low-contrast area for the carrier label — a dark printed panel underneath a white label looks like a printing error and some carriers reject or surcharge it.
