From rough FDM layer lines to professional-quality finishes. Every smoothing method compared — pick the right one for your material and skill level.
Fastest (ABS only)
Acetone vapor smoothing — 30-60 min, no sanding needed
Best for PLA
Filler primer + sanding, or XTC-3D epoxy for glass-smooth finish
Professional results
Filler primer → 400-800 grit → spray paint → clear coat
Universal method. Start with 120-220 grit to remove layer lines, finish with 400-1000 for a smooth surface.
Sand rough, spray filler primer, sand again when dry. Primer fills micro-scratches and reveals remaining defects. Best overall method.
Acetone vapor dissolves ABS surface — no sanding needed. Sealed container with acetone-soaked cloth. Fire hazard — take precautions.
Brush-on two-part epoxy that self-levels and fills layer lines. Cures hard and sands/paints beautifully. Best for PLA finishing.
Brush UV resin (like Elegoo, Anycubic) over print, cure with UV lamp. Fast, hard surface. May need multiple coats for deep layer lines.
Quick pass with heat gun or lighter softens PLA surface. Easy to ruin prints — practice on scraps first. Good for small touch-ups.
This is the best all-around method for PLA, PETG, and ABS. Takes 3-6 hours but gives professional results.
Remove supports and clean
Remove all supports and sand off any stubborn support marks. Clean print with IPA to remove oils. Let dry 5 minutes.
Sand with 120-220 grit
Remove the most prominent layer lines. Sand in the direction of the layers, then across. Don't worry about perfection — you're just removing the biggest bumps.
Spray filler primer
Apply 2-3 thin coats of gray filler primer (Rust-Oleum, Duplicolor). Light coats — don't flood the surface. Wait 10 minutes between coats. Let cure 30-60 minutes.
Wet-sand 400 grit
Dip sandpaper in water and sand the primer coat smooth. The primer reveals remaining imperfections — focus on those areas. Rinse and let dry.
Second primer coat (if needed)
If layer lines are still visible, apply another coat of primer. For most prints, one coat is enough after step 4.
Final sand 800-1000 grit
For ultra-smooth results, wet-sand the final primer coat with 800-1000 grit. This gives a near-painted surface ready for color.
Paint and clear coat
Apply color coat (spray paint or airbrush). Finish with clear coat for protection and gloss/matte final look.
Fire hazard. Acetone is highly flammable. Never use near open flame, sparks, or heat sources. Work in a well-ventilated area away from electronics.
What you need: Acetone (hardware store / nail polish remover 100%), glass or metal container with lid, something to elevate the print above the liquid.
Process: Pour 15-20ml of acetone in bottom of container. Place print on an elevated platform (not touching liquid). Seal container. Wait 30-60 minutes. Remove print and let off-gas for 30 minutes in open air before touching.
Results: Layer lines disappear almost completely. Surface looks injection-molded. Detail may soften — 30 min is usually the sweet spot; longer = softer, more rounded features.
| Material | Best Method | Avoid |
|---|---|---|
| PLA | Filler primer + sanding, XTC-3D epoxy | Acetone (does nothing), heat gun (easy to ruin) |
| PETG | Sanding + filler primer | Acetone (partial effect, unreliable), aggressive heat |
| ABS | Acetone vapor (fastest), filler primer | Nothing specific — ABS is the most post-processable |
| ASA | MEK or acetone (partial), filler primer | Acetone is less effective than on ABS |
| TPU | Avoid sanding — ruins flex. Accept layer lines. | Sanding (removes flex properties), chemical smoothers |
| Wood PLA | Sand + stain (part of the aesthetic) | Heavy primer (hides wood texture) |