How to Choose the Right Sanding Disc Grit
Why Grit Selection Matters
Choosing the wrong sanding disc grit is one of the most common — and costly — mistakes in finishing work. Go too coarse and you leave deep scratches that take hours to sand out. Go too fine too early and you're wasting time and discs without removing material efficiently. This guide cuts through the confusion so you can pick the right grit the first time.
Understanding the Grit Scale
Grit numbers refer to the number of abrasive particles per square inch. The lower the number, the coarser the abrasive and the more aggressively it removes material. Higher numbers mean finer abrasives that leave smoother surfaces.
Coarse Grits: 40–80
Best for: Heavy material removal, stripping old paint or coatings, shaping wood, removing rust from metal, leveling uneven surfaces.
Coarse grits cut fast and leave visible scratches, so they're a starting point — not a finishing step. Use 40-grit for the most aggressive stock removal, 60-grit for general stripping and shaping, and 80-grit when you need speed but want slightly less aggressive scratching.
Tip: Never skip more than one grit step. Jumping from 60 to 180 leaves deep scratches that finer grits can't fully remove.
Medium Grits: 100–150
Best for: Blending, smoothing after coarse sanding, preparing bare wood or metal for primer, removing light surface defects.
120-grit is the workhorse of most sanding sequences — it removes the scratches left by coarser grits while still cutting efficiently. 150-grit is ideal for final prep before primer on automotive and woodworking projects.
Fine Grits: 180–220
Best for: Final sanding before finish coats, scuff-sanding between coats of paint or clear coat, smoothing raised grain on wood.
At this stage you're refining the surface, not removing material. 180-grit is a common final step before primer or stain. 220-grit is used between finish coats to knock down dust nibs and improve adhesion.
Very Fine Grits: 240–400
Best for: Wet sanding, polishing between clear coats, ultra-smooth final finishes on lacquer or varnish.
These grits are used in the final stages of finishing. 320-grit is popular for scuff-sanding cured clear coat before the final coat. 400-grit and above are used for wet sanding to achieve a glass-smooth surface before buffing and polishing.
Quick Reference: Grit by Application
| Application | Starting Grit | Finishing Grit |
|---|---|---|
| Stripping paint / heavy removal | 40–60 | 80–120 |
| Bare wood prep for stain | 80–100 | 150–180 |
| Auto body primer prep | 80–120 | 150–180 |
| Between paint coats | 220 | 320 |
| Wet sanding clear coat | 400 | 800–1500 |
| Metal rust removal | 60–80 | 120–180 |
Choosing the Right Disc for Your Sander
Grit is only part of the equation. You also need to match the disc to your sander size and backing type. Browse our full range of sanding discs by size and backing:
Popular Disc Series by Grit Range
Not sure which Indasa series is right for your application? Here are some of our most popular options across grit ranges:
- Indasa 5" Rhynogrip WhiteLine Solid Sanding Discs — available in a wide grit range, ideal for general finishing
- Indasa 5" Rhynogrip RedLine Solid Sanding Discs — premium performance for demanding applications
- Indasa 5" Rhynostick HeavyLine PSA Sanding Discs — PSA backing for high-production use
- Indasa 6" Rhynogrip WhiteLine Solid Sanding Discs — great for larger orbital sanders
- Indasa 8" Rhynogrip WhiteLine Solid Sanding Discs — for wide-area sanding
The Golden Rule of Grit Progression
Always work through grits in sequence — don't skip more than one step at a time. Each grit removes the scratches left by the previous one. Skipping steps means you're trying to remove deep scratches with a fine abrasive, which takes far longer and uses more discs than doing it right the first time.
A typical sequence for automotive refinishing might look like: 80 → 120 → 180 → 220 → 320 → 400. For woodworking: 80 → 120 → 150 → 180.
Ready to Stock Up?
Now that you know which grit you need, browse our full selection of Indasa sanding discs — available in every grit from 40 to 400+ across multiple sizes and backing types. Have a question about which disc is right for your job? Contact us and we'll help you find the right fit.