The rule of thumb: skip one grit max
Going from 80 to 220 by skipping 120, 150, and 180 leaves deep scratches that show through stain and finish. The professional rule: never skip more than one grit step. Going 80 → 120 → 180 → 220 is acceptable. Going 80 → 180 is not.
This is because each grit only removes the scratches left by the previous coarser grit. If 180 leaves scratches deeper than 220 can remove in a reasonable time, you'll see those scratches forever.
What each grit range does
- 40-60 (extra coarse): Removing thick finishes, dimensioning. Never use on veneer or thin stock — removes material fast.
- 80-100 (coarse): Initial sanding of rough lumber, removing mill marks, stripping old paint.
- 120-150 (medium): General-purpose. Removes scratches from coarser grits. Ready for staining most woods.
- 180-220 (fine): Pre-finish sanding. Standard for paint and stain prep. Stain will absorb slightly less, giving lighter color.
- 320-400 (very fine): Between finish coats. Removes dust nibs, smooths the surface.
- 600-2000 (extra fine): Polishing finishes, wet sanding between topcoats, polishing to high gloss.
How to know when you're done with a grit
- Look at the wood from a low angle with light across the surface. Any shiny spots or scratches mean you need more sanding with that grit.
- Wipe with a damp cloth — the water raises the grain and reveals any remaining scratches.
- For stain prep: stop when the wood feels smooth to a bare fingertip and shows no visible cross-grain scratches.
- For finish sanding: stop when the previous grit scratches are completely gone.
Common sanding mistakes
- Skipping grits: Saves time on the front end, costs much more in finish rework. Don't.
- Too much pressure: The sander's weight is enough. Pressing harder generates heat that burns the wood and burns through paper fast.
- Sanding end grain with face grain: End grain absorbs more and tears out. Use a backer block to support it, or sand across the end grain with finer grit.
- Not vacuuming between grits: Coarse grit dust under fine-grit paper scratches the surface. Vacuum (or wipe with a damp rag) between grits.
- Using fresh paper on detail areas: A folded piece of used paper gives better control on curves and edges.
Hand sanding vs power sanding
- Hand sanding: Better control, less aggressive, easier on curves. Slower. Use with a sanding block for flat surfaces to prevent rounding.
- Random orbital: Standard for most shop work. 5" or 6" pads are typical. Use dust extraction.
- Sheet sander: Less expensive, rectangular pad. Better for corners and edges than random orbital. Leaves swirl marks.
- Drum / wide belt: Production sanding. Aggressive material removal. Not typically for hobbyists.
When to use a sanding sealer
A sanding sealer (dewaxed shellac or commercial sealer) goes on before the topcoat. It:
- Seals the grain so the topcoat builds faster
- Reduces the number of topcoats needed
- Gives a smoother final surface (sands easily to powder)
- Can add a slight amber tone (with shellac)
Don't use sanding sealer under lacquer, hardwax oil, or any finish that needs to penetrate — it defeats the purpose. Use it under poly or varnish when you want a glass-smooth finish.
Frequently asked questions
Can I reuse sandpaper?
Yes, until it stops cutting. Knock off the dust by rubbing two pieces together, or use a sandpaper cleaning stick (abrasive block). Store in a dry place — humidity ruins paper.
What's the difference between aluminum oxide and silicon carbide?
Aluminum oxide is the standard for wood — tough, long-lasting, brown color. Silicon carbide is sharper but more brittle — better for metal, plastic, and between-coat finish sanding. Garnet is the old-school natural abrasive for fine hand-sanding.
Should I use a dust collector or shop vac?
Yes. Sanding dust is a health hazard (especially hardwood dust, which is a known carcinogen). A shop vac hooked to your sander is the minimum. A full dust collector is better for production work.