Common Abrasives + Sanding Reference
Why this matters
Wrong abrasive = ruined surface, ruined sandpaper, lost time. Coarse grit on finish work = scratches the customer sees forever. Fine grit on heavy stripping = forever. Match grit + sander + technique to the surface + the product. This is the field card.
Grit scale (CAMI + FEPA grading)
CAMI (Coated Abrasives Manufacturers Institute - U.S.) + FEPA (Europe) differ slightly. Common practical grits:
- 40 - 60: extra coarse; heavy stripping, removing old finish, leveling rough lumber
- 80 - 120: coarse to medium-coarse; smoothing rough surface, preparing for finish
- 150 - 180: medium; between coats, smoothing patches
- 220 - 320: fine; final smoothing before primer / topcoat
- 400 - 600: very fine; between finish coats on smooth substrates
- 800 - 2000: ultra-fine; polishing, automotive
- 2000+: rubbing compound territory
Rule: never skip more than 2 grit increments. 60 → 100 → 150 → 220 typical wood progression.
Abrasive material
Aluminum oxide: most common; cheap; medium life. General-purpose wood + metal.
Garnet: traditional wood-sanding; cuts fast on wood; dulls quickly on metal.
Silicon carbide: harder; for metal, plastic, glass; wet-sanding capable.
Zirconia alumina: tough; for metal sanding (grinder discs, belt sanders).
Ceramic (3M Cubitron, Norton SG): premium; longest life on hard metal.
Diamond: hard tile, glass, concrete.
Backing material
Paper (A, B, C, D, E weights): lighter = more flexible; heavier = more aggressive. C-weight typical for hand sanding.
Cloth backing: more durable than paper; flexible; belt sanders + sleeves.
Film (Mylar): tear-resistant; consistent thickness; auto finish work.
Mesh / screen: drywall sanding (clog-resistant).
Pads (foam-backed): conforms to curves; sanding moldings.
Common forms
Sheets (9 × 11): hand sanding + sanding block.
Quarter-sheets: fits palm sander.
5" / 6" PSA discs: stick-on for orbital sander.
5" / 6" hook + loop discs: removable for orbital sander.
Belts: 3 × 21, 4 × 24, 3 × 18, 4 × 36 (belt sander sizes).
Sleeves (drum sander): for spindle sander.
Sanding sponges: foam-back sandpaper; for curves + corners.
Sanding screens (mesh): drywall finishing.
Sanding wood
Roughing stock to flat: 60 - 80 grit belt sander OR random-orbit.
Smoothing: 100 - 150 grit.
Final pre-finish: 180 - 220 grit (most water-based finishes); 220 - 320 (lacquer / shellac).
Between finish coats: 320 - 400 grit (knock down nibs).
Sanding with grain on softwood: prevents scratches that show through finish.
Sanding any direction on hardwood + plywood: random-orbit OR fine grit.
Sanding metal
Removing rust: 40 - 80 grit cloth OR flap disc.
Smoothing weld: 60 - 80 grit grinder; refine 120 - 220.
Polishing: 220 → 400 → 800 → 1500 progression.
Aluminum: 220 - 400 grit; don't use steel wool (corrosion).
Cleaning before paint: 80 - 120 grit; rough surface for paint key.
Sanding drywall (finishing)
Joint compound sanding: 120 - 220 grit screen OR sanding sponge.
Don't oversand: feathers out OR rubs paper face off drywall.
Vacuum + dust extraction: drywall dust is fine + travels far.
Pole sander: 12" sanding head; reaches ceiling without ladder.
Wet-sanding (sponge): for tight spots OR avoiding dust.
Sanding paint (prep)
Removing failed paint: 60 - 80 grit (wood) OR scraper.
Feather edges: 120 - 180 grit.
Final pre-paint: 220 grit.
Sand between coats: 220 - 320 grit (lightly).
Cabinet refinishing: 120 → 180 → 220 progression.
Vintage furniture stripping: chemical stripper + scraping + light sand.
Sander types
Random-orbit sander (5" disc): most versatile; doesn't leave swirl marks. Daily use.
Palm sander (1/4 sheet): smaller area; finer detail.
Belt sander (3 × 21 OR 4 × 24): aggressive material removal; flat surfaces.
Detail sander (triangle): corners + tight spaces.
Drum sander (spindle): edges + curves.
Power file: small belt sander for tight spaces.
Multi-tool (oscillating): with sanding pad; corners + flush sanding.
Hand sanding tools
Sanding block (wood OR cork OR foam): flat sanding; even pressure.
Sanding sponges: contours.
Pole sander: reach high without ladder.
Sanding stick / file: tight spots.
Common sanding mistakes
Skipping grits (60 directly to 220 = scratches remain). Wrong abrasive for material (garnet on metal = quick fail). Too much pressure (loads up sandpaper + heat + uneven surface). Sanding wet OR humid material (paper loads up quickly). Sanding against grain on softwood (visible scratches). Not vacuuming between grits (residual grit transfers + scratches). Reusing dull paper (slow + ugly).
Vacuum + dust extraction
Dust mask / respirator required: N95 minimum; P100 for lead OR silica dust.
Vacuum attachment on sander (Festool, Bosch): captures most dust at source.
Shop vacuum + HEPA filter: for room cleanup.
Ventilation: drywall dust + paint dust spread far; close interior doors.
Wet sanding
Silicon carbide sandpaper rated for wet use.
Water OR solvent as lubricant: prevents paper loading.
Automotive paint finishing: 1000 - 3000 grit wet.
Polishing compound after: final smoothing.
Tile + stone: wet sanding for polished finish.
Sanding safety
Eye protection: dust + flying particles.
Respirator: N95 minimum; P100 for lead OR silica.
Hearing protection: power sanders > 85 dB.
Gloves: skin protection from heat + abrasion (some prefer bare hands for control).
No loose clothing / jewelry: catches in sander.
Specialty sanding situations
Lead paint (RRP-certified work): HEPA vacuum mandatory; full PPE; controlled disposal.
Asbestos (transite, older drywall mud, older floor tile): DON'T sand; specialty abatement.
Silica dust (concrete, masonry): N95 minimum (P100 preferred); OSHA silica rule applies.
Mold (water-damaged drywall): containment first; mold respirator; HEPA vacuum.
Truck stock
Random-orbit sander + 5" hook-loop discs (60, 80, 120, 180, 220, 320 grits), belt sander + assorted belts, hand sanding block + sheets (80, 120, 220 grit), sanding sponges (medium + fine), drywall pole sander + screens (120, 180), shop vacuum, dust masks (N95).
The single most-impactful sanding habit is the VACUUM BETWEEN GRIT INCREMENTS. After finishing a pass with 80 grit, vacuum (OR wipe with tack cloth) the surface BEFORE the 120 grit pass. Residual 80-grit particles will scratch the surface as the 120 paper moves over them - defeating the smoother grit's purpose. Same applies between every grit step. The 30 seconds vacuuming saves the rework + delivers genuinely smooth final surface. Customer's "perfect finish" comes from clean transitions between grits.
References
- CAMI + FEPA grit grading standards
- Manufacturer technical data (3M, Norton, Mirka, Festool)
- ASTM D4214 (paint surface evaluation)
- Manuall internal: PPE Selection by Task, Common Drill Bits