Pillowing appears as small bumps or rough patches on the top surface of a print, where the material fails to fully bridge over the infill pattern below. The result is an uneven, pockmarked finish on flat top surfaces.
Common Causes
- Insufficient top layers — Too few solid layers cannot fully close over the infill gaps
- Layer height too high — Thicker layers have less overlap and bridge poorly over gaps
- Inadequate cooling — Without enough airflow, top layers sag into infill voids before solidifying
- Low infill percentage — Large gaps between infill lines make bridging more difficult
- Print speed too fast — Material is deposited too quickly to settle flat on top layers
Recommended Fixes
- Increase top solid layers to at least 5-7 (or 1.2mm+ total top thickness)
- Lower layer height for the top layers (0.12-0.16mm works well)
- Increase part cooling fan to 100% for top layers
- Reduce print speed for top layers to 15-25mm/s
- Increase infill density to 25% or higher to provide better support for top surfaces
- Use a rectilinear or monotonic top infill pattern for smoother finishes