How to Sand 3D Printed PLA Parts Smooth (320, 400, 600, 1000 Grit Guide)

3D printing creates amazing possibilities—but the layer lines left on PLA prints can look rough and unpolished. The secret to turning your print into a professional-looking model is careful sanding with the right grit sequence. This guide shows you how to sand PLA parts step by step using 320, 400, 600, and 1000 grit sandpaper.

Why Sanding PLA Matters

PLA prints often show visible layer lines, support marks, or rough textures. Sanding removes these imperfections, making surfaces smooth for painting, priming, or final display. A proper grit progression avoids scratches and ensures a polished finish.

Essential Tools for PLA Sanding

• 320–1000 grit wet/dry sandpaper – silicon carbide sheets work best.
• Sanding block or sponge – keeps pressure even across curved prints.
• Water spray bottle – prevents heat buildup and clogging.
• Microfiber cloth – wipes away sanding residue.
• Optional filler primer – fills small gaps after sanding.

Best Grit Sequence for PLA Prints

• 320 grit: Removes layer lines and support scars.
• 400 grit: Refines scratches left by coarse sanding.
• 600 grit: Smooths surfaces for priming or painting.
• 1000 grit: Creates a polished finish before painting or clear coating.

Step-by-Step Process

1. Start with 320 grit. Focus on high spots and layer ridges. Use 320 grit (25-pack) for consistent shaping.
2. Smooth with 400 grit. Even out the surface and refine sanding marks. Stock up with 400 grit (100-pack).
3. Refine with 600 grit. Lightly wet sand to achieve a uniform, satin-like finish. Try 600 grit (50-pack).
4. Finish with 1000 grit. This step preps your print for painting or leaves it smooth enough for display. Use 1000 grit (10-pack).
5. Optional filler primer. If deep layer lines remain, spray filler primer, let dry, then sand again with 600–1000 grit.

Special Cases

For complex models, use sanding sticks or wrap sandpaper around small objects for precision. For large flat panels, always use a sanding block to avoid unevenness. If your print is heat-sensitive, avoid dry sanding at high pressure—wet sanding keeps PLA cool and prevents melting.

Pro Tips

• Always wet sand finer grits (400+) to reduce scratches.
• Sand in circular motions for even results on curved surfaces.
• Change sheets often—PLA dust clogs paper quickly.
• Use primer as both a filler and a surface tester—uneven spots show immediately.

Aftercare

• Seal PLA prints with clear coat or paint after sanding for durability.
• Store sandpaper flat in a dry place to prevent warping.
• Wear a mask—PLA dust is fine and can irritate lungs.

FAQs

• Can I skip straight to 600 grit? Not recommended—320 and 400 remove layer lines much faster.
• Do I always need filler primer? Only for deep ridges or imperfect prints. High-quality prints may not need it.
• Can PLA be polished after sanding? Yes—with 1000 grit followed by plastic polish, you can achieve a glossy finish.

Watch & Learn

For smooth 3D printing results, explore our fine grit sandpaper collection.