How to inspect cold foil and hot foil in the same pass
Cold foil and hot foil can be seen in the same pass, but in two regions. Cold foil is judged on whether the pattern transferred into place. Hot foil is also judged on pinholes and filled edges from temperature and pressure. One sensitivity either reports normal foil grain as a defect, or lets pinholes pass.
Cold foil and hot foil can be seen in the same pass, but they need two regions. Cold foil is judged on whether the pattern transferred into place. Hot foil is also judged on pinholes and filled edges caused by temperature and pressure. One sensitivity either reports the normal foil grain as a defect, or lets the pinholes pass.
Why it is judged this way
The edge of cold foil is often less sharp than hot foil. That is a process difference, not a register failure. The template must be this job’s signed sample. Do not use an old template from the other kind of foil. Pinholes are raised on the dirt table only inside the hot-foil region.
What to compare
| What you see | Call it | Do not |
|---|---|---|
| The cold-foil edge is slightly feathered | Compare it with the signed sample first | Scrap it at once as a register failure |
| Pinholes in the hot-foil layer | Judge them as foil dirt | Treat them as printed white spots and add ink |
| Foil grain is reported as dirt | Loosen the texture sensitivity of this layer | Lower the sensitivity of the whole label |
Check at a job change or a new roll
- Build one region for cold foil and one for hot foil.
- Use the signed sample to confirm whether the cold-foil feathering was already there.
- Place one pinhole sample only in the hot-foil zone and confirm it alarms.
