What does a fine reverse line look like when the plate is clogged?
When a fine reverse line is clogged on the plate, the fine line that should expose the substrate is filled with ink, making it look like a white line is missing from a solid area. It is the same type of fill-in as plugged type, but the location is a line rather than a counter. If the white line returns after plate washing or reducing ink, it is clogging; if the line is still absent after washing, then it was never on the plate or in the file.
When a fine reverse is plugged, the fine line that should expose the substrate is filled with ink, making it look like a white line is missing from a solid. It is the same kind of fill-in as plugged-together characters, but the location is a line rather than a character counter. If the white line returns after washing the plate or reducing ink, it is plugging; if the line is still absent after washing, then it was never on the plate or in the file at all.
Is the line still on the plate?
There is a fine reverse on the approved proof or printing plate, but on the printed sheet that line has become the same solid as its surroundings, perhaps with a few white dots remaining in the middle. This is because the blank areas in the cells or on the plate are plugged by dried ink, and ink has spread across them. If you reduce ink and wash the plate, the white line will open up again. If it is washed clean and the ink is also reduced, and the white line still does not exist, check the plate and the file; no amount of washing on press will wash out a line that was never there.
Fine reverses plug more easily than solids because the blank area is too narrow, and dried ink and pressure can seal it shut. So do not use whether the solid looks good to judge that this color is not plugged.
Wash or remake the plate?
| After washing the plate and reducing ink | Conclusion | Next step |
|---|---|---|
| White line returns | Plate plugging | Record the ink amount for this color and the interval between press stops for plate wiping |
| White line still absent | Plate or file | Check the printing plate and file; do not keep reducing ink |
| Only a fixed section is missing | That section is completely plugged or the plate is damaged | Treat only that section |
Do this first this round
- Align it with the approved proof to confirm that what is missing is a reverse that originally existed.
- First wash this color and reduce ink, then print a sheet to see whether the line returns.
- If it does not return, stop the press and check the plate; do not keep printing the surrounding solid lighter and lighter.
