How to Sand ABS Plastic: for Scratch Removal (Flat Panels)

When you sand abs plastic, the goal is a controlled scratch pattern: remove defects quickly, then refine the surface so it looks even and the next coat (or polish) bonds cleanly. All eQualle silicon carbide sheets are suitable for wet or dry use—pick the method that keeps the surface cooler and the paper from loading up.

Why Sanding Matters

Sanding isn’t just about “making it smooth.” It’s about leveling highs and lows, removing damaged material, and stepping through grits so each pass erases the scratches from the previous one. Skipping grits often leaves haze, visible lines, or edges that catch light differently.

Recommended Tools

• 9x11 in silicon carbide sandpaper sheets (wet or dry use)
• Sanding block or soft hand pad (helps keep pressure even on flats)
• Spray bottle with clean water + a drop of dish soap (for wet sanding)
• Microfiber towels and a tack cloth (for dust control before recoating)
• Masking tape (to protect adjacent edges and corners)
• Good lighting (raking light shows scratches and low spots)

Recommended Grit Sequence

• 220 grit
• 320 grit
• 400 grit
• 600 grit
• 800 grit
• 1000 grit

Step-by-Step

1. Clean the surface thoroughly. Remove oils, waxes, and loose debris. On plastics/resins, a mild soap wash and a final water rinse helps prevent deep random scratches caused by grit contamination.
2. Mask edges and details you don’t want to round over. Corners sand faster than flats, so protect sharp lines with tape if they must stay crisp.
3. Start your first pass with the coarsest grit in your sequence. Use light-to-moderate pressure and long strokes. If you’re wet sanding, keep the surface evenly wet and wipe slurry often. For this stage, use 400 Grit (100-pack) when you’re focusing on fast, even leveling without gouging.
4. Switch direction 90° on the next grit. This makes it easy to see when the previous scratch pattern is fully removed before moving on.
5. Move to mid-grits to erase the coarse scratches. Keep pressure lighter than you think you need—let the abrasive do the work. For most projects, the “sweet spot” is a steady rhythm with frequent wipe-downs. Use 800 Grit (100-pack) in this refining stage to reduce haze and unify the finish.
6. Rinse or vacuum between grits. One stray coarse particle can create a deep scratch that forces you to step backward.
7. Finish with the highest grit in your plan for the look you want: a matte, satin-ready surface (for recoating) or a pre-polish surface (for gloss). Use 1000 Grit (100-pack) with very light pressure to dial in clarity and reduce visible lines.
8. Inspect under bright, angled light. If you see isolated deep scratches, spot-sand that area back one grit and blend outward, then re-run the higher grit to match.
9. Final cleanup: rinse (wet) or wipe (dry), then let the surface fully dry before recoating. If you’re polishing, move to compound/polish only after the sanding scratches are uniform.

Special Cases

Avoid overheating: plastics soften with friction. Wet sanding helps keep temperature down and prevents smearing.

Use a soft pad on curved areas to prevent flat spots; use a block on flat panels to avoid waves.

If the paper loads up, rinse it or switch to a fresh sheet—loaded abrasive can drag and scratch.

Pro Tips

• Use a pencil “guide coat” scribble on dull surfaces; sand until the marks disappear to confirm you’re level.
• Change sheets early. Fresh abrasive cuts cooler and leaves a more consistent scratch pattern.
• Don’t jump more than ~2 grit steps. Smaller jumps remove previous scratches faster and reduce rework.
• Keep your hand relaxed and pressure even—most swirl marks come from uneven pressure or contaminated paper.

Aftercare

• For recoating: wipe with a clean, lint-free cloth and follow the coating manufacturer’s prep instructions.
• For polishing: start with a compound appropriate for your material, then finish with a finer polish.
• Store leftover sheets flat and dry; creased paper can cut unevenly and leave random deep lines.

FAQs

• Wet or dry—what’s better for abs plastic? Wet sanding usually reduces heat and clogging; dry sanding is faster to set up. Use wet when you need cleaner scratch control or when the material loads paper quickly.
• How do I know when to move to the next grit? When the entire surface shows a uniform scratch pattern from the current grit with no visible lines from the previous grit.
• Why do I still see scratches after finishing? Most often you skipped a grit, used uneven pressure, or carried contamination to a higher grit. Step back one grit and re-finish with clean rinse/wipe-downs.

Watch & Learn

Tip while you watch: pause at each grit change and compare scratch direction—if the previous scratches are still visible, stay on the current grit a bit longer before moving up.

Need to stock up for your next project? Browse the full sandpaper lineup here: eQualle sandpaper collection.