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PETG blobs and zits

Symptom: Small bumps, scars or deposits appear on walls and seams.

Most likely causes

  • Wet filament
  • Over-extrusion
  • Oozing during travel
  • Seam placement

Test in this order

  1. Dry PETG before changing slicer values.
  2. Calibrate flow with a measured-wall test.
  3. Run a temperature tower and avoid excessive nozzle heat.
  4. Set a deliberate seam location and compare the same model.
Stop changing multiple settings at once. Save the model, filament condition and room conditions, then change one variable and compare.

Relevant starting profiles

PETG settingsChoose your printer for a hardware-aware profile

Reviewed 2026-07-22. Results vary by filament formulation, moisture, nozzle and slicer.