Rough Top Surface
Fix a rough or scarred top layer — dry the filament thoroughly, then calibrate flow rate if the surface is still rough.
A finished top surface should have joined extrusion lines without open gaps, raised ridges, or sagging patches. Some visible line texture is normal. Diagnose the shape and location of the roughness before changing settings.
Start with dry filament and flow calibration. If those checks do not resolve the surface, inspect top-layer speed, the roof's support, and nozzle contact.
Read the Surface
| Appearance | First check |
|---|---|
| Irregular pits, inconsistent texture, or popping during printing | Filament dryness |
| Raised ridges between lines; nozzle drags through material | Flow and Over-Extrusion |
| Open spaces between lines | Flow or Under-Extrusion |
| Roof sags mainly over infill openings | Top thickness and support |
| Scratches follow travel moves | Raised material, nozzle deposits, and travel settings |
| Only the bottom layer is rough | First Layer Calibration |
Let the print finish before judging the roof. The first solid layer over infill can look different from the final top layer.
1. Dry and Repeat
Use Filament Drying for the loaded material. This is especially relevant to moisture-sensitive engineering materials, but do not assume a new spool is dry.
Repeat the same small part with a broad, flat top using the matching stock printer, nozzle, and material profiles. Keep its top-layer count, infill, orientation, and speed unchanged so the comparison isolates drying.
Photograph the completed surface in consistent lighting. If it improves, save the drying conditions and confirm the result before adjusting flow.
2. Calibrate Flow
Follow Material Tuning. For an untuned material, establish temperature and Pressure Advance before its flow test. The supplied tests require dry filament and a 0.4 mm nozzle; follow the guide's requirements.
Choose the flow result with joined lines and no raised ridges. Reducing flow until the roof has gaps is not an improvement. Save the multiplier in the material profile, re-slice, and repeat the same part.
If extrusion remains intermittent, investigate the filament path rather than compensating with a higher multiplier. If excess material affects walls as well, follow Over-Extrusion.
3. Compare Top-Layer Speed
If the material is dry and flow is calibrated but the roof remains rough, lower the speed specifically for the top solid layers. Leave temperature, flow, and the rest of the geometry unchanged.
Check the preview to confirm which layers use the edited setting. Compare surface quality and whether the lines still join. Save the setting only if the improvement repeats; one universal top speed does not suit every material and nozzle.
4. Check Roof Thickness and Infill Support
When sagging follows the infill openings:
- Inspect the sliced preview at the transition from infill to solid top layers.
- Check the total top thickness, not only the layer count. The same count produces a thinner roof at a smaller layer height.
- Increase top thickness and repeat the test.
- If openings remain poorly supported, compare more supporting infill or a different infill pattern separately.
- Keep cooling appropriate to the material profile. Do not apply another material's fan percentage as a general fix.
Use Infill vs Walls and Layer Times & Cooling for the related settings.
5. Inspect Scratches and Consider Ironing Last
If the nozzle scratches the top, first check for raised excess material and external nozzle deposits. Compare travel and Z-hop settings with the stock profile. A travel change does not fix over-extrusion.
Once ordinary top layers are sound, ironing can be tested as an optional finish on suitable flat surfaces. It adds a finishing pass and print time; it does not repair a weak or incomplete roof. See Prusa's Ironing documentation for the slicer feature.
Verify the Result
Inspect a finished, cooled part. The top should be continuous, with no open gaps, raised ridges, or sagging over infill. Check that walls and dimensions did not become worse while tuning the roof.
Record the Diagnostic Results
Keep a top close-up and side view together with material and drying details, the calibration result, top thickness, infill settings, and the slicer project. This record helps compare each change and lets support distinguish flow, speed, and roof-support problems.
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