Grit number tells you how coarse or fine an abrasive is: the lower the number, the bigger the grain and the faster (and rougher) it cuts. The single most common sanding mistake is skipping grits — each grit's job is to erase the scratches left by the one before, so work in steps and never skip more than one.
Grit Selection Chart
| Grit | Class | Typical use |
|---|---|---|
| 36–60 | Coarse | Heavy stock removal, stripping old finish, leveling rough-sawn lumber, aggressive shaping |
| 80–100 | Medium-coarse | Shaping, flattening glue-ups, removing planer/mill marks, first pass on most raw wood |
| 120–150 | Medium | General smoothing after shaping; the workhorse range for bare-wood preparation |
| 180–220 | Fine | Final pass before stain or finish; softwoods usually stop at 180, hardwoods at 220 |
| 240–320 | Very fine | Sanding between finish coats (light pressure), knocking down raised grain and dust nibs |
| 360–600 | Extra fine | Wet sanding lacquer and varnish, smoothing final coats, pre-polish on metal |
| 800–2000+ | Polishing | Wet color-sanding automotive finishes, polishing solid surface, plastics and metal |
Which Mineral?
- Aluminum oxide — the all-purpose choice for wood and metal. Tough, long-lasting, economical. If in doubt, start here. (sheets, belts, rolls)
- Silicon carbide — harder and sharper; cuts glass, solid surface, plastics and finishes cleanly, and works wet for dust-free fine sanding. (wet/dry sheets, belts)
- Premium engineered abrasives — lines like Mirka Abranet (mesh, dust-free) and Abralon (foam-backed, contours) hold their cut longer and leave more uniform scratch patterns; worth it for production work and fine finishing. (Mirka range)
A Simple Progression That Works
For most bare-wood projects: 80 → 120 → 180, then finish. Add 220 for hardwoods or blotch-prone species before stain. Between finish coats, a light pass at 320 keeps things flat. For metal headed to polish: 120 → 240 → 400 wet → 600 wet, then buff.
Common Questions
What grit removes paint fastest without gouging?
Start at 60 on flat areas, 80 if the substrate is soft. Move up to 120 as soon as the bulk is off.
What grit between coats of polyurethane?
320 by hand with light pressure — you're leveling dust nibs, not cutting through the film.
Do higher grits always mean a better finish?
No — on bare wood, sanding past ~220 can burnish the surface and cause blotchy stain absorption. Save the very fine grits for finish films and metal.
Still unsure? Call us at (800) 516-7621 — we stock what we sell and use what we stock.