Sand concrete garage slab to prep for epoxy coating and remove lai...

When sanding a concrete garage slab, most problems come from heat, pressure, and dust. This guide sands to prep for epoxy coating and remove laitance through 120–400 grit with simple risk controls: light pressure, steady motion, and frequent wipe-down.

Let the abrasive cut—don’t force it.

Why Sanding Matters

Sanding removes defects and creates the surface profile for the next stage. Deep scratches left behind can show through after paint, clear coat, or polishing. A controlled progression makes the finish predictable.

Recommended Tools

• Sandpaper sheets
• Sanding block/pad
• Dust mask / respirator + eye protection
• Microfiber cloths
• Vacuum/brush
• Masking tape

Recommended Grit Sequence

Use the sequence below in order. Inspect between steps and only move up when older scratches are removed.

• 120 grit: keep pressure light; avoid heat buildup.
• 180 grit: keep pressure light; avoid heat buildup.
• 220 grit: keep pressure light; avoid heat buildup.
• 320 grit: keep pressure light; avoid heat buildup.
• 400 grit: keep pressure light; avoid heat buildup.

Step-by-Step

1. Protect adjacent areas. Tape trim, edges, and nearby surfaces you don’t want to scuff.
2. Control dust and safety. Use a dust mask/respirator and keep dust down with vacuuming and wipe-downs.
3. Clean first. Remove oils and dust so the paper cuts evenly.
4. Start with 120 grit. Use even strokes and a block where possible to avoid waves.
5. Wipe and inspect. Confirm one consistent scratch pattern before moving up.
6. Step up through 180 and 220 grit. Slightly change direction between grits and reduce pressure.
7. Refine with 320 grit. Keep motion steady; avoid sanding in one spot.
8. Finish with 400 grit. This sets your final surface profile for prep for epoxy coating and remove laitance.
9. Final cleanup. Vacuum/brush, then wipe with a clean cloth before the next stage.

Special Cases

If a deep scratch appears late, drop back one grit step and remove it before continuing.

Pro Tips

• Swap sheets when they stop cutting; clogged paper can leave random scratches.
• Reduce pressure as grits get finer.
• Wipe between grits so inspection is accurate.
• Use a block on flats to avoid finger grooves.
• If the surface starts to heat up, stop and let it cool. Heat can worsen scratches and clog paper.

Aftercare

• Remove dust from seams and corners before coating.
• If wet sanded, dry fully before primer/paint/clear coat.
• Store unused sheets flat and dry.
• Discard heavily loaded sheets so old finish doesn’t re-scratch the surface.

FAQs

• Can I skip a grit? Skipping often leaves deeper scratches that show later. Use the sequence for predictable results.
• How do I know when to move up? When the scratch pattern is uniform and you can’t find lines from the previous grit under angled light.
• Why does the finish still look uneven? Usually because the first grit step wasn’t completed or debris re-scratched the surface.

Watch & Learn

Here are the exact grits referenced in this workflow so you can match the sequence: 100 grit (pack of 25), 2000 grit (pack of 25), 1500 grit (pack of 100).

• 100 Grit Sandpaper Sheets — Pack of 25
• 2000 Grit Sandpaper Sheets — Pack of 25
• 1500 Grit Sandpaper Sheets — Pack of 100

Complete each grit step, inspect under angled light, and keep pressure light at the end. That’s the simplest route to a finish-ready surface.