When Is a Pinhole in Carton Hot Foil Stamping Considered Unacceptable?
A hot foil stamping pinhole is a small hole in the foil layer that exposes the substrate. If it falls on a logo, text, or barcode, it is unacceptable no matter how small. If it falls on a large solid foil area, it may only be released according to the diameter and count in the customer's dirt chart. If the chart does not specify it, stop and ask; do not set an acceptable size yourself.
Foil stamping pinholes are small holes in the gold layer that expose the underlying color. If one falls on a logo, text, or barcode, no matter how small, it counts as a reject. If one falls on a large solid gold area, it may only be released according to the diameter and count in the customer’s dirt spec table. If it is not written on the table, stop and ask; do not decide for yourself on a size that still looks acceptable.
What is visible in the pinhole
If what is visible in the pinhole is paper or the printed background color, the gold did not cover it, or that spot did not adhere during stamping. If the pinholes repeat around the circumference of the foil stamping die, check whether that spot on the die is damaged or has low pressure. If the pinholes are randomly scattered, it is more often the foil itself, temperature, or paper dust. For both, first decide whether they can be released based on location, then investigate the cause. Even after the cause is found, the batch that already has them on the logo still cannot be released.
For pinholes on large solid gold areas, customers sometimes use the same table as for printed dirt specks. Use that table; do not separately say “gold is more noticeable, so it is stricter” or “gold is less visible, so it is looser,” unless the contract says otherwise.
Location
| Pinhole on | Is there a dirt spec table? | Action |
|---|---|---|
| Logo, text, barcode | Regardless | Reject |
| Large solid gold area | Yes, and within limits | Release per table and retain sample |
| Large solid gold area | No | Stop and ask customer |
Do this first this round
- First check whether the pinhole falls on text or on the gold area.
- For those on text, mark them as reject immediately, then measure whether they repeat around the die circumference.
- For those on the gold area, compare only against the written diameter and count.
