White streaks in folds may be in the ink, coating, or paper substrate. To handle it, you need to determine at what stage the error appears. Just changing the color to make the stain less visible does not solve the cause.
See errors before and after each step
Keep the printed sheet sample, the lamination or coating sample and the folded sample. Compare error location, folding direction, paper code and thickness. Check if errors appear on all edges or just one direction to localize the cause.
The creasing tool needs to be suitable for the type and thickness of the cardboard, according to the material manufacturer's technical instructions. Quantitation cannot replace thickness measurements when choosing processing methods.
Make a control sample for each factor
| Factor | Test direction |
|---|---|
| Paper and fiber direction | Compare the sample to the artwork according to the confirmation configuration |
| Create folds | Check tools, grooves and machining conditions |
| Finishing layer | Compare before and after rolling or coating |
Test each element individually: paper, fiber direction, creasing tool or finish. The manufacturing unit needs to confirm the change with a sample. Do not apply one groove parameter to all paper types.
Browse by explicit acceptance level
Uniform acceptable appearance at visible edges and when opening the box. Capture errors under the same conditions, save passing samples for purchasing and quality control departments to compare.
If the thread stain appears after the customer opens the lid, the browsing session must involve opening and closing operations. A pre-built box image may miss this error.
Will increasing paper thickness stop cracking?
Increasing the paper thickness may change the creasing and fit requirements of the box. Need to try again instead of assuming thick paper will stop cracking.
Send SquareBag error samples and current specifications to find the cause, try the solution and finalize the comparison sample.
Reference source
Explore Packaging printing or Exchange specifications with SquareBag.
See the Printing Techniques group