How to Sand Wood Properly

Sanding is the least popular job in woodworking and the one that most visibly decides whether a project looks made or looks homemade. It is also the step where beginners lose the most time, because almost everyone does it in a way that takes longer and produces a worse result.

The core idea is simple and rarely stated: sanding does not make wood smooth. It replaces big scratches with small ones. Every grit you use leaves its own scratch pattern, and the next grit exists to remove the previous one. Once you see it that way, every rule below becomes obvious.

Choosing where to start

Start at the coarsest grit the surface actually needs — and no coarser, because every coarse scratch is work you have created for yourself.

• 80 grit — planer ripple, rough saw marks, removing real material, leveling a glue-up.
• 120 grit — the usual start for dressed lumber with minor marks. Most beginner projects begin here.
• 150 or 180 grit — an already-good surface, or wood that has been hand planed or scraped.

And if what is wrong is the shape rather than the surface — a curve that is not fair, a corner that is not round enough, a part a whisker too fat — no grit fixes that. Sanding takes the high and low spots down together. Correct the shape with a rasp or a file first, then sand what is already right.

If in doubt, test on the worst area. If 120 removes the defect in a reasonable time, start at 120; if you are still working at it after a minute, drop to 80.

The progression, and the one rule about it

Work up one step at a time: 80, 120, 150, 180. You can occasionally skip one step. You cannot skip two.

The reason is arithmetic rather than tradition. A 180-grit disc removes material very slowly; asked to erase 80-grit scratches, it will take far longer than a pass at 120 followed by a pass at 180 would have. Skipping grits does not save time — it moves the time to the grit least equipped to do the work.

At each grit, sand the whole surface. Half of the swirl marks that show up under finish are places where the previous grit was never fully removed because attention drifted to one area.

When to stop

Going finer is not automatically better, and there is a real point past which it becomes counterproductive.

• Oils, stains and penetrating finishes — stop at 150 to 180. These have to soak in, and sanding finer closes the pores so the wood absorbs less — which shows up as a pale, patchy result.
• Film finishes (polyurethane, water-based, lacquer) — 180 to 220. A film sits on the surface rather than soaking in, so a finer, more consistent surface is worth having. Our sanding discs and grits guide has the full grit-by-grit breakdown.
• Before staining — consistency matters more than fineness. Sand everything to exactly the same grit, everywhere, or the stain will show the difference. Do not be tempted past 180 here.
• End grain — one or two grits finer than the faces. End grain absorbs far more finish and looks much darker unless you close it down.

The two steps almost everybody skips

1. Raking light

Hold a light almost parallel to the surface, or take the piece to a window and look along it. Scratches, dents, glue spots and missed areas that are completely invisible looking straight down show up unmistakably in raking light.

Do this at every grit, not just at the end. A defect found at 120 costs thirty seconds; the same defect found after the first coat of finish costs an evening.

2. Raising the grain

Sanding cuts some surface fibers without removing them, and they lie flat until they get wet. Then they swell and stand up, and your first coat of a water-based finish feels like fine sandpaper.

The fix takes ten minutes: wipe the surface with a damp cloth, let it dry completely, then sand very lightly at your final grit to shear off the raised fibers. Do it once and the finish goes on smooth. This matters most with water-based finishes and water-based stains, and it does no harm before an oil-based one.

The final pass, by hand

A random orbital sander leaves faint circular scratches. On bare wood you cannot see them; under stain or oil, you can see them clearly and permanently.

The fix is a light final pass by hand at the same grit, with the paper wrapped around a firm block, sanding along the grain. It replaces the circular scratches with straight ones that run in the direction the eye already expects, so they disappear.

Use a block, not your fingers. Finger pressure rounds over crisp edges and digs into softer growth rings, which is the other reason surfaces come out uneven.

Technique that actually matters

• Do not press down. A random orbital works by floating its pad across the surface. Pressing tips the pad, digs the edge in and slows the orbit — producing exactly the swirl marks you are trying to avoid. Let the machine’s weight do the work.
• Keep it moving, slowly. A steady pace of about an inch per second, with each pass overlapping the last by half. Dwelling in one spot dishes the surface.
• Sand along the grain by hand, any direction by machine. The random orbital’s whole point is that direction does not matter to it. Hand sanding is the opposite — across the grain leaves scratches that never come out.
• Change the paper. Worn abrasive burnishes rather than cuts, and it generates heat. If sanding suddenly feels slow, the disc is finished. Paper is far cheaper than your time.
• Ease the edges last. A couple of light passes with a folded sheet along each sharp corner. It makes the piece feel finished, and it stops finish pulling away from a knife-sharp edge.

Dust: the part that ruins finishes

Sanding dust in a finish is the most common defect in beginner work, and it comes from three places: the surface, the air, and your clothes.

1. Vacuum the surface, then the bench, then the floor. In that order.
2. Let the air settle. Fine dust stays airborne for a long time — an hour is not excessive.
3. Wipe the surface immediately before finishing with a cloth lightly dampened with the same solvent your finish uses: water for water-based, mineral spirits for oil-based.

This dust is also the thing you are breathing, and sanding is the tool you use for the longest continuous stretches. Wear a rated respirator rather than a nuisance mask, and read dust collection for a small shop for the garage setup.

What to use

Tool	Why you need it	Price
Bosch ROS20VSC 5 in Random Orbit Sander	A 5-inch random orbital does ninety percent of the sanding in a first shop, at every grit.	$99.00
Diablo Hook and Lock ROS Sanding Discs, 5 in, 120 Grit, 50-Pack	The grit you use most, in a quantity that means you actually change them when worn.	$22.97
3M Pro Grade Precision Sanding Sheets, Assorted Grits 80/120/180	Assorted sheets for the hand-block final pass and for anywhere the machine cannot reach.	$15.99
Scottchen Cork Sanding Block, 4-1/4 x 2-3/8 x 1-3/16 in	For the last pass along the grain. Stays flat, so it will not round over a crisp edge.	$9.99
3M 8511 N95 Cool Flow Valved Respirator (10-pack)	Sanding dust is the finest in the shop and you breathe it for the longest. Not a nuisance mask.	$24.99
Starter kit subtotal		$172.94

Live Amazon prices as of August 31, 2026; they change, and we don’t display stale numbers — a tool with no live price shows “Check price” and is left out of the subtotal. #ad How we’re funded.

The short version

Start at the coarsest grit you genuinely need. Move up one step at a time, covering the whole surface each time. Check under raking light. Raise the grain if the finish is water-based. Take a final pass by hand along the grain. Stop at 150 to 180 for an oil or stain, 180 to 220 for a film finish. Clean the dust off properly.

Seven steps, none of them difficult, and together they are most of the difference between a project that looks amateur and one that does not. Next: how to apply a wood finish.