Ink cracking on corrugated flute

Ink on corrugated cracks when a brittle film is asked to flex with the flute or the score. The board moves. The ink does not.

Checks

1. Flex a sheet over a flute and across a score. Cracks that only appear there are brittleness, not a press void.
2. Confirm the ink is meant for that board. A film that is fine on coated paper can crack on kraft.
3. A heavy coat cracks more than a thin one. Cut the film before you add a brittle coating on top.
4. Let the ink dry fully, then flex again. Some cracks only show after the sheet has cooled.

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