How to inspect a laminate after it is already sealed
On a laminate that is already sealed, you can still see bubbles, trapped dirt, wrinkles, and print defects that show from the outside. A shift between layers that you cannot see cannot be measured after lamination.
On a laminate that is already sealed, you can still see bubbles, trapped dirt, wrinkles, and print defects that show from the outside. A shift between layers that you cannot see cannot be measured after lamination. Do not write in the report that every layer was inspected. Bubbles need transmitted light or side light, not ordinary straight light forced onto them.
Why it is judged this way
Dirt trapped between two films is often only a faint shadow under straight light. Side light or transmitted light lights the edge of a bubble. If you cannot see it, change the light. Do not raise the threshold until the paper grain alarms everywhere. A layer that is already sealed cannot have its register put back. You can only decide whether to accept it.
What to compare
| What you see | What to call it | What not to do |
|---|---|---|
| A bright ring under side light | Call it a bubble or trapped dirt | Treat it as a print white spot and add ink |
| A missing print that shows from the outside | You can judge it | Claim the inner layer was inspected too |
| Register between layers can no longer be seen | Write that it was not inspected | Add a pass |
At job change or when a roll is opened
- At the station after lamination, use light that can see a bubble.
- Use a known bubble and confirm the alarm.
- The conclusion on register between layers comes only from before lamination.
