Sand PETG 3D Print: Smooth Layer Lines for Paint

This guide shows how to smooth layer lines for paint on a 3D printed PETG enclosure using silicon carbide sheets for wet or dry use. The priority is a uniform scratch pattern—so move up only when the previous grit’s scratches are fully removed under bright raking light.

Keep everything clean, use consistent backing, and reduce pressure as grits get finer.

Why Sanding Matters

Clarity restoration, paint adhesion, layer-line smoothing, patch blending, and orange peel leveling all depend on scratch depth and consistency. If you jump grits too fast or sand with contamination, deeper scratches remain and show up later as haze or visible lines.

Recommended Tools

• Sanding block + soft interface pad (for edges and curves)
• Spray bottle (water + a drop of dish soap) for wet sanding
• Microfiber towels + lint-free wipes
• Bright flashlight for raking-light inspection
• Masking tape for edges/corners
• Clean rinse bottle/bucket to keep slurry free of grit

Recommended Grit Sequence

• 150 grit
• 320 grit
• 600 grit
• 800 grit
• 1000 grit
• 1200 grit
• 1500 grit
• 2000 grit

Wet sanding often gives better control on fine finishing steps by reducing loading and contamination scratches.

Step-by-Step

1. Clean the 3D printed PETG enclosure and remove oils/dust. Dry fully before sanding.
2. Pick a starting grit based on defect depth. Start as fine as possible while still cutting effectively.
3. Sand evenly with overlapping passes using consistent backing. Wipe clean and inspect under raking light until uniform. For a controlled working step, use 1200 Grit (25 Pack).
4. Move up one grit at a time. Don’t advance until earlier scratches are gone everywhere you can inspect.
5. For fine refinement, wet sand and rinse often to keep slurry clean and avoid random deep scratches. For refinement with less loading, step up to 150 Grit (50 Pack) with wet sanding.
6. Finish at the final grit for the next step (polish, paint, or resin coat), then clean thoroughly. For final cleanup passes (or an alternate pack), keep 320 Grit (50 Pack) ready.

Special Cases

Polycarbonate clarity: Keep slurry clean and pressure light—contamination scratches are the #1 cause of haze.

ABS/PETG paint prep: Aim for a uniform matte surface with no glossy spots. Protect sharp edges.

Fiberglass patch blending: Feather outward with a softer pad so the transition disappears under resin.

Pro Tips

• Use raking light every grit—overhead light hides defects.
• Change direction slightly between grits to confirm scratch removal.
• Replace sheets early when they load and stop cutting cleanly.
• Reduce pressure as you go finer to keep scratches shallow.

Aftercare

• Rinse/wipe sanding residue and dry completely before finishing.
• Remove masking tape slowly to avoid adhesive residue.
• Store leftover sheets flat and dry.

FAQs

• Wet or dry use? Both. Wet sanding often reduces clogging and improves scratch visibility.
• When do I move up a grit? When you can’t find any scratches from the previous grit under raking light.
• Why do I still see haze/lines? Usually leftover scratches from an earlier grit—step back one grit and re-sand cleanly.

Watch & Learn

Use the video to compare scratch patterns between grits. If you still see older lines, stay on that grit longer before moving up.

For more wet/dry silicon carbide sanding sheets and grit options, visit eQualle on Amazon.