Sheet & material defect
Blushing in thermoforming
Also called: Whitening, blush
Blushing is a whitish or hazy appearance — most visible on clear or dark parts — that appears where the material has been over-stretched or stressed, scattering light at the surface.
Why it happens
- Over-stretching in deep draws or tight radii
- Sheet slightly too cool while forming
- Excessive plug or forming force in one area
- Material sensitive to stress-whitening (e.g. some PP, PETG)
How to fix & prevent it
- Reduce local draw / increase radii
- Raise sheet temperature into the ideal window
- Distribute material with a plug assist to cut peak strain
- Select a grade less prone to stress-whitening
How Indu prevents it: We tune temperature and material distribution to keep strain within the grade’s limits — and advise the right grade up front — so clear and dark parts stay blush-free.
Troubleshooting help
Fighting blushing on a part?
Send your drawing, sample or a photo of the issue — our engineers will diagnose the cause and reply with the tooling, material and process fix, usually within 24 hours.
ISO 9001:2015 certified · Most quotes back within 24 hours