Surface streaks or discolouration can come from contaminated filament, worn nozzles, unstable temperature, moisture or pigment variation. Separate material defects from printer conditions.
Inspect the part
- Streaks follow layers or travel.
- Colour changes with position.
- Dark specks or bubbles.
- Occurs on one spool only.
Check the machine
Clean or replace the nozzle, verify temperature stability and inspect the feeder and PTFE path for debris.
Verify material
- Dry the spool.
- Check diameter.
- Compare another batch.
- Keep a sample.
| Signal | Possible cause | Action |
|---|---|---|
| Dark streaks | Contamination | Clean/replace nozzle |
| Uneven colour | Pigment or heat | Compare batch |
| Bubbles | Moisture | Dry |
| Positional marks | Geometry | Inspect path |
Common engineering mistakes
- Changing several settings.
- Ignoring nozzle wear.
- Comparing different batches.
- Judging under changing light.
- Not keeping samples.
Buyer checklist
- Is the nozzle clean?
- Is temperature stable?
- Is material dry?
- Does another spool behave the same?
- Is the defect repeatable?
Send photos and spool details through our support form.