What Sandpaper Should You Use?
Project type, material hardness, and desired finish determine the correct sandpaper grit. Lower grit numbers contain larger abrasive particles and remove material aggressively. Higher grit numbers contain smaller particles and smooth or polish surfaces.
Key determinants:
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Material type determines abrasion requirement (wood, metal, plastic, drywall).
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Project stage determines grit selection (stripping, leveling, finishing).
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Finish type determines surface smoothness requirement.
Example relationships:
| Factor | Effect on Grit Choice | Example |
|---|---|---|
| Material hardness | Harder materials require durable abrasives | Steel requires silicon carbide |
| Project stage | Early stages require coarse grit | Paint removal uses 40–80 grit |
| Finish requirement | High-gloss requires very fine grit | Polishing uses 400+ grit |
What do sandpaper grit numbers mean?
Sandpaper grit numbers represent abrasive particle size. Lower numbers indicate coarse abrasive grains that remove material quickly. Higher numbers indicate fine grains that smooth surfaces.
Example interpretation:
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60 grit removes paint and heavy imperfections.
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120 grit smooths bare surfaces.
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220 grit prepares surfaces for finishing.
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400+ grit produces polished surfaces.
The following table provides a general sandpaper grit classification.
| Grit Range | Category | Typical Use |
|---|---|---|
| 24–60 | Extra coarse | Heavy stripping and shaping |
| 60–80 | Coarse | Removing paint or varnish |
| 100–150 | Medium | Surface smoothing |
| 180–220 | Fine | Final surface preparation |
| 320–600 | Extra fine | Finishing and polishing |
What is the general sandpaper grit guide?
Sandpaper grit ranges map directly to sanding tasks and surface preparation stages. Each grit range performs a specific material removal or smoothing function.
General Sandpaper Grit Guide
| Grit Range | Grade | Purpose |
|---|---|---|
| 40–80 | Coarse / Medium | Removes heavy material, strips old paint or varnish, shapes wood, removes deep scratches or gouges |
| 100–150 | Medium / Fine | Performs general sanding, smooths bare wood, prepares surfaces for paint or film finishes |
| 180–220 | Fine / Very Fine | Performs final sanding before finishes, scuffs glossy surfaces for recoating, smooths between primer coats |
| 240–400+ | Very Fine / Extra Fine | Sands between finish coats, removes dust nibs and brush strokes, performs polishing or wet sanding |
Example usage:
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Furniture refinishing uses 80 → 120 → 180 → 220 grit progression.
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Automotive polishing uses 320 → 600 → 1000 grit wet sanding.
What are the key sanding principles for best results?
Correct sanding technique requires progressive grit usage and surface evaluation. Proper progression removes scratches created by earlier abrasive stages.
Key Sanding Principles
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Start with coarse grit to remove major imperfections or old finish layers.
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Progressively switch to finer grits to remove scratches from the previous grit.
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Maintain consistent sanding pressure to prevent uneven surfaces.
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Inspect the surface between grit changes to ensure scratch removal.
Example sanding progression:
| Project | Typical Grit Progression |
|---|---|
| Furniture restoration | 80 → 120 → 180 → 220 |
| Wood tabletop finishing | 120 → 150 → 180 → 220 |
| Automotive paint sanding | 400 → 600 → 800 → 1000 |
Why should you avoid skipping sandpaper grits?
Skipping sandpaper grits leaves deeper scratches that finer abrasives cannot remove efficiently. Each sanding stage removes scratch patterns from the previous abrasive.
Example issue:
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60 grit creates deep scratches
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Jumping directly to 180 grit fails to remove those scratches
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The scratches remain visible after finishing
Recommended progression rule:
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Increase grit gradually by 50–100 grit steps
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Maintain sequential sanding stages
Example proper progression:
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80 → 120 → 180 → 220
How does the finish type affect sandpaper choice?
Different finishing products require different sanding levels because they interact with wood surfaces differently.
Film finishes
Film finishes sit on the surface and hide minor sanding scratches.
Examples:
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Paint
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Polyurethane
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Lacquer
Recommended sanding range:
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150–180 grit before application
Penetrating finishes
Penetrating finishes absorb into the wood and highlight surface scratches.
Examples:
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Wood stain
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Tung oil
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Linseed oil
Recommended sanding range:
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180–220 grit for even absorption
Example comparison:
| Finish Type | Surface Behavior | Recommended Grit |
|---|---|---|
| Paint | Covers surface | 150–180 |
| Polyurethane | Forms protective film | 180 |
| Wood stain | Penetrates fibers | 180–220 |
| Oil finishes | Absorb into grain | 220 |
Why should you test sandpaper on scrap material?
Testing sanding progression on scrap wood identifies the correct grit sequence before finishing the main project. Different wood species respond differently to abrasion.
Examples:
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Pine sands quickly and requires lighter pressure.
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Oak resists abrasion and requires longer sanding.
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Maple highlights sanding scratches under stain.
Testing benefits:
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Confirms the correct grit progression.
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Prevents visible scratches after finishing.
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Ensures uniform stain absorption.
Common test methods:
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Sand a hidden area of the project.
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Sand a separate piece of identical wood.
Testing ensures predictable finishing results and reduces sanding errors.
