ExtrudoWhy is my 3D print blobs at color or filament change?
Blobs at color or filament change is usually caused by leftover plastic from the old filament wasn't fully purged before the new color started printing. A blob or color smear appears right at the point where filament was changed
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Quick reference
| Defect | Most likely cause | First thing to try |
|---|---|---|
| Blobs at color or filament change | Leftover plastic from the old filament wasn't fully purged before the new color started printing | Increase purge volume |
What it looks like
A blob or color smear appears right at the point where filament was changed
Most likely cause
Leftover plastic from the old filament wasn't fully purged before the new color started printing
How do I fix blobs at color or filament change? Step-by-step
- 1
Increase purge volume
Raise the purge/prime amount in your slicer or multi-material settings so more of the old color is pushed out first.
Done when: New color prints clean with no streaks of the old color
- 2
Use a purge/prime tower
Enable a purge tower next to the model to catch the transition ooze away from the visible print.
Done when: Transition mess appears on the tower, not the model
Frequently asked
What causes blobs at color or filament change in 3D prints?
Leftover plastic from the old filament wasn't fully purged before the new color started printing
How do I fix blobs at color or filament change on my printer?
Follow the step-by-step fix above, starting with "Increase purge volume". Each step includes a "done when" check so you know whether it worked before moving on.
Is this fix confirmed by other makers?
This entry is part of Extrudo's seeded defect library. Confirmation counts appear once real users report the fix worked.
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