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Choose grit by what you need it to do
On bare hardwood, sanding has two jobs: remove defects left by milling or scraping, then leave a surface smooth enough for the finish. The right grit depends on the condition of the wood, not just the species. Starting too fine leaves dents and machine marks in place; starting too coarse creates scratches that take extra work to erase.
For a typical new hardwood floor or furniture panel with modest milling marks, begin around 80 grit and work through 100 or 120 grit. A rough, cupped, or heavily scratched surface may need 36 or 40 grit first, while clean, well-planed stock may need only 100 or 120 grit. Always test an inconspicuous spot before committing to a full grit sequence.
A practical grit guide
| Grit | Best use on bare hardwood | What to watch for |
|---|---|---|
| 36–40 | Leveling severe unevenness, removing old finish or deep damage | Removes wood fast; easy to leave gouges and dish edges |
| 60 | Removing prominent planer marks or scratches after coarse work | Usually too aggressive as a routine starting point on flat, clean boards |
| 80 | Common first cut on average unfinished flooring and rougher panels | Must be followed by finer grits to remove its visible scratches |
| 100–120 | Refining a surface before many penetrating stains or clear finishes | Going finer can reduce stain absorption and make color uneven |
| 150–180 | Light final sanding on some furniture and clear-finish projects | Often unnecessary on floors; may burnish wood before staining |
Grit numbers describe abrasive size: lower numbers cut more aggressively. A 40-to-120 jump is too large for most work because the finer abrasive may polish the tops of coarse scratches without removing their bottoms. A useful rule is to move up one standard step at a time—such as 40, 60, 80, 100—though an initial 80 can usually go to 100 or 120 if it has removed defects evenly.
Inspect before buying abrasives
Look across the wood under raking light, with the light almost parallel to the surface. Mark dents, glue smears, raised grain, and cross-grain scratches in pencil. After sanding, the pencil marks show whether you have covered the area evenly. On a floor, inspect edges and the center separately; the large machine and edge sander can leave different scratch patterns.
Hard species such as maple and oak tolerate ordinary sanding well, but dense maple can show uneven stain absorption if it is over-sanded or burnished. Open-pored oak can hide some fine scratches in its texture, while scratches across its grain remain conspicuous under stain. Pine is softer and more prone to scallops and rounded edges from aggressive sanding. Reduce machine pressure and check it often rather than assuming the same pass count will work for every board.
Match the abrasive and tool to the job
For a floor, use abrasives made for the machine you are renting, in the specified size and attachment style. A drum or belt sander cuts quickly but can leave dips if held still or started before it is moving. Keep it moving, overlap passes consistently, and avoid stopping with the abrasive against the floor. An orbital sander is slower for leveling but less likely to make deep, straight gouges.
For furniture and small panels, a random-orbit sander with hook-and-loop discs is convenient. A random-orbit sander and compatible discs are a reasonable choice for broad, flat surfaces; a sanding block is better for narrow areas and controlled hand work. Cheap paper is fine for a small project or occasional use, but it can clog or lose its cut faster. If you are sanding a large floor, consistent, durable machine abrasives usually save time and reduce the risk of uneven cutting.
Use a vacuum connected to the sander where practical. Dust reduces visibility, loads the abrasive, and can contaminate stain or finish. Wear a properly fitted respirator rated for fine particulates, along with eye protection; hardwood dust is not harmless. Vacuum the surface between grits rather than wiping it with a dirty shop rag.
Sand in a sequence, then check your work
Start with the finest grit that will remove the defects you can actually see. If 80 grit removes the milling marks, do not begin at 40 merely because the abrasive is available. Sand evenly, vacuum, then inspect under raking light before moving up. On a typical sequence, 80 removes defects, 100 or 120 removes the 80-grit scratches, and a light final pass at 150 may suit a clear-finished tabletop. The finish manufacturer’s instructions should decide the final grit, especially for stain.
Do not skip a grit when deep scratches remain. A common failure is sanding with 40, jumping to 100, then discovering dark lines after stain. Stain makes scratches stand out because they absorb more pigment. Return to the grit that can remove the scratch, then work forward again. Also avoid pressing hard: extra pressure can slow the sander, leave swirl marks, and wear the abrasive unevenly. Let a clean, sharp disc cut.
Stop at the right grit for the finish
For penetrating stain, many floors are sanded to 100 or 120 grit, but follow the stain label and test the actual wood. Sanding too fine can close or burnish the surface, leaving stain pale or blotchy. Before staining, vacuum carefully and apply stain to a sample area or spare board prepared with the same grit sequence. If you want a very smooth clear finish on furniture, 150 or 180 may be appropriate, but finer is not automatically better.
Between coats of water-based finish, follow the finish maker’s directions; that light de-nibbing is different from sanding bare wood. Bare wood should be uniformly smooth, not polished glossy. If a surface looks shiny in patches before finishing, check for uneven sanding or burnishing rather than adding finer grit everywhere.
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