Sanding Grit Progression Guide
How it works
Sanding efficiently requires moving through grit sequences in the correct order — skipping grits leaves scratches that show through finish. The Sanding Grit Progression Guide recommends the grit sequence for a starting condition and desired final finish level.
**Grit numbering system** Lower numbers = coarser grit. Common sequences: 80 (coarse, material removal), 120 (medium), 150, 180, 220 (fine, pre-finish), 320, 400 (finish sanding or between coats). The CAMI (North American) and FEPA/P-grade (European) systems use slightly different scales at finer grits.
**Progression rules** Never skip more than one grit size. Each grit removes scratches left by the previous, coarser grit. If you can see previous scratches after sanding, continue at the current grit before advancing. Sand with the grain on solid wood — sanding across the grain leaves scratches that are visible under finish.
**By application** Raw wood preparation: 80, 120, 150, 180, 220. Between finish coats: 320 to 400, or 0000 steel wool. Wet sanding final coat: 800, 1,000, 1,500, 2,000. Final polish on automotive finish: 2,000, 3,000, compound, polish.
**Sanding tools** Random-orbit sanders minimize cross-grain scratches by combining rotation with orbital motion. Belt sanders remove material fast but can easily gouge if held stationary. Hand block sanding ensures flat surfaces for finish coats.
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Frequently Asked Questions
- Solid wood surfaces that will receive a clear or stained finish: always sand with the grain. Cross-grain scratches are much more visible under finish than with-grain scratches because they interrupt the natural grain lines. For paint-grade surfaces where grain won't show: cross-grain scratches are acceptable but still not ideal — they can telegraph through paint on flat panels. For shaping or removing material quickly: initial passes can be diagonal to grain, but always finish with the grain before applying any finish. On veneer plywood: sand very carefully with the grain at all times — cross-grain sanding on thin veneers can cut through to the glue layer in seconds, ruining the panel.
- Each coat of finish (polyurethane, lacquer, shellac) raises the grain slightly and creates micro-bumps from dust particles that settled during drying. Wet sanding between coats with 320–400 grit (dry) or 800–1,000 grit (wet) levels these bumps and gives the next coat a better mechanical bonding surface. Wet sanding (using water or mineral spirits as lubricant) prevents clogging of fine-grit paper and cuts more evenly than dry sanding at the same grit. On the final coat: wet sanding with 1,000–2,000 grit removes orange peel texture, followed by polishing compound and paste wax for a mirror finish. Don't sand through to bare wood — use light pressure and check frequently.
- Mill marks are the ripple pattern left by planer or surfacer blades — they appear as evenly spaced waves across the face grain. Start at 80 grit if marks are deep, 100–120 grit if moderate. The marks are perpendicular to the grain (blades are perpendicular to grain direction) — sanding with the grain at 80 grit removes them efficiently. Confirm they're gone by wiping with mineral spirits (wet wood shows mill marks clearly) before advancing to the next grit. Never start finer than 100 on lumber with mill marks — you'll spend far too long removing them with fine paper. After 80: proceed 120, 150, 180, 220 before finishing.
- Yes — drywall and wood use very different grit ranges. Drywall finishing: 100–120 grit for knocking down dried joint compound, 120–150 for finish sanding before primer, 220 for very fine finish. Drywall work uses open-coat paper to prevent clogging from gypsum dust. Wood finishing: starts coarser (80 grit for rough lumber) but finishes finer (220 before stain, 320–400 between finish coats, 800–2,000 for final polishing). The key difference: drywall compound is much softer than wood and clogs sandpaper quickly — always use large sheets or a pole sander that allows paper to flex, and change paper frequently.