Why Web Wrinkling Is Mistaken for a Printing Defect
When the web wrinkles before printing, the crease can cut off or double the image, making it look like a printed streak. The diagnosis is simple: if the crease extends to the unprinted film or paper edge, it is web-handling wrinkling, not a plate or ink problem. Only if the crease exists solely within the image and the material is flat does it point back to a printing defect.
The web first wrinkles and then prints; the crease cuts through the artwork or prints double, looking like a printed bar. The judgment is simple: if the crease extends to the film edge or paper edge where there is no artwork, it is web wrinkling during transport, not a problem with the plate or ink. Only if the crease exists solely in the artwork and the web is flat does it go back to being a printing defect.
Why inspection marks it as a printing defect
The camera only compares the artwork. When a crease passes through a solid area, that strip becomes lighter or turns into a double line and does not match the approved proof, so the system draws a red box. It does not know that this line was already on the film before printing. If the operator increases pressure as if dealing with ink piling or misregistration, the web will wrinkle even more.
First pull out the unprinted film edge and hold it up to the light. If the same crease is still there, the cause is tension, the flattening roller, or the incoming material. If the film edge is flat and only the ink area has a double line, then it may be a loose plate, uneven backing paper, or slipping during impression.
Check the web first or the plate first
| Blank edge | Line on the artwork | Check first |
|---|---|---|
| Has the same crease | Lighter or printed double along the crease | Tension, flattening roller, incoming material |
| Is flat | Only a double line in the artwork | Plate mounting, backing, pressure |
| Crease only a few meters after a splice | Follows the splice | The splice itself; do not change tension for the whole roll |
Do this first this round
- When the red box appears, first feel and look at the blank edge; do not touch the ink first.
- If the blank edge has a crease, check the tension in that section and look backward from the splice or roll change.
- Once you confirm the web is flat, then send this line to check the plate and pressure.
