What sanding is for
Sanding replaces the marks of the last tool — the planer, the saw, a scraper that chattered — with a uniform field of fine scratches the finish will hide. The Forest Products Laboratory notes that clear and glossy finishes accentuate planer marks and raised grain rather than hiding them, so the work under the finish decides how it looks. A sharp plane or a card scraper can leave a surface that needs little or no sanding; see using a card scraper.
The sequence
Start with the finest grit that removes the existing marks quickly, then step up. Each grit only has to remove the scratches of the one before; skipping too far leaves deeper scratches that the finer paper takes a long time to reach, and that stain finds first. Watco's instructions for its Danish Oil give one such sequence — #120, #150, #180, then #220 — and Aqua Coat's for its grain filler go from #120 to #220. What the numbers mean, and why US and European grades part above 220, is on the grit chart.
Sanding a board
Mark the surface
Draw light pencil squiggles across it. When the marks are gone at a grit, that grit has reached the whole surface.
Sand with the grain
Minwax and Watco both say to sand in the direction of the grain; cross-grain scratches show under stain.
Keep the paper flat
A block or a sander's pad keeps edges crisp and stops the paper dishing soft earlywood between harder latewood.
Clean between grits
Remove the dust before the next grit — a loose coarse grain left on the surface scratches it again.
Stop at the finish maker's grit
See the table below; the grit belongs to the product going on, not to the wood.
End grain soaks up far more — the Forest Products Laboratory puts it at about 100 times as porous as side grain — so it darkens under stain. Many finishers sand end grain a grit finer than the faces to close it a little; test on an offcut.
Where makers say to stop
| Product | Maker | Sand to | Note |
|---|---|---|---|
| Wood Finish (oil-based stain) | Minwax | #220 | With the grain; remove dust |
| Gel Stain | General Finishes | No finer than 150 (hardwoods), 180 (softwoods) | GF's species grouping |
| Dye Stain | General Finishes | No finer than 220 (closed-grain), 180 (open-grain) | Raise the grain first |
| Arm-R-Seal (oil-based topcoat) | General Finishes | Up to 220; finer not recommended | Too smooth can reduce adhesion |
| Polyx-Oil (hardwax oil) | Osmo | P180–240 furniture; P120–150 floors | European P-grades |
| High Performance Wood Filler, before stain | Minwax | No finer than 100 | Over-sanding closes the filler's pores |
Each maker's instruction for its own product. They differ by more than a grade; follow the product you use.
Note— Finer is not always better
General Finishes warns that sanding a surface too smoothly can reduce adhesion, and its stain instructions stop well short of the 220 Minwax asks for. Sanding past the maker's figure works against its instructions, and General Finishes ties an over-smooth surface to poorer adhesion.
Water-based finishes and raised grain
Water swells the fibres that sanding laid down, leaving a fuzzy surface after the first coat. Minwax's answer for its water-based Polycrylic is to dampen the wood before the final sanding, let it dry, then take the raised grain off with #220; General Finishes says the same before its water-based Dye Stain. Oil-based stains such as Minwax Wood Finish do not raise the grain, Minwax says.
Dust
Safety— Sanding dust and old paint
OSHA links wood dust to dermatitis, allergic and other respiratory effects, and cancer; collect it at the source and wear respiratory protection — Osmo's instructions, for one, call for a dust mask while sanding. On old painted furniture, assume a layer may contain lead: EPA lists refinishing old furniture as a source of lead exposure. Read refinishing furniture before sanding any old paint.
After sanding: choosing and applying a finish
- What kind of finish: wood finish types — film-forming or penetrating — and food-safe finishes for items that touch food.
- Colour: wood stain, then how to stain.
- Clear coats: polyurethane and applying it; shellac and lacquer; oils; wax.
- Opaque: paint and primers.
- Before finishing: fillers for holes and open pores; sandpaper itself.
- Old finishes: stripping and refinishing furniture; applying any finish in finishing techniques.
Before the first coat
- Every machine and tool mark gone at the coarsest grit
- Sanded with the grain at each grit, dust removed between grits
- Stopped at the grit the finish maker gives
- Grain raised and knocked down if the finish is water-based
- End grain and filled areas tested on an offcut
- Dust cleared from the surface and the room
Sources
Grits are each maker's instructions for its own product, as published; they are not a standard, and the Osmo figures are European P-grades. Workshop stopping points for common finishes are on the sandpaper grit chart. Abrasive grading systems are explained there and not repeated here.
- 1.
Product Data Sheet, Minwax Wood Finish (MWX132). Minwax, 2026.
Used for: Sanding with #220 grit in the direction of the grain and removing the dust before Minwax Wood Finish stain.
- 2.
Technical Data Sheet, Gel Stain. General Finishes, 2020.
Used for: Sanding no finer than 150 grit on hardwoods and 180 on softwoods before General Finishes Gel Stain, in GF's grouping of species.
- 3.
Technical Data Sheet, Dye Stain. General Finishes, 2020.
Used for: Sanding no finer than 220 on closed-grain and 180 on open-grain woods before General Finishes Dye Stain; wetting and re-sanding to reduce grain raising.
- 4.
Technical Data Sheet, Arm-R-Seal. General Finishes, 2020.
Used for: Sanding progressively finer up to 220 grit, and the warning that sanding finer than 220 is not recommended and sanding too smoothly can reduce adhesion.
- 5.
Product Information, Polyx-Oil Original. Osmo, 2020.
Used for: Final sanding of P180–240 for furniture and P120–150 for floors under Polyx-Oil, and wearing a dust mask while sanding.
- 6.
Technical Data WAT-02, Watco Danish Oil. Rust-Oleum (Watco), 2020.
Used for: A sanding sequence of #120, #150, #180 and #220 before Watco Danish Oil, and removing dust with a vacuum, tack cloth or rag.
- 7.
Technical Data Sheet, Clear Wood Grain Filler (130-099). Aqua Coat.
Used for: Sanding #120 then #220 before grain filler.
- 8.
Technical Data Sheet, Minwax High Performance Wood Filler. Minwax.
Used for: Sanding a cured filler repair no finer than 100 grit before staining it, because over-sanding closes its pores.
- 9.
Minwax Product Guide. Minwax.
Used for: Raising the grain with water and knocking it down with #220 before a water-based finish; sanding between coats with #220.
- 10.
Christopher G. Hunt. Wood Handbook: Wood as an Engineering Material (FPL-GTR-282), Chapter 16: Finishing Wood. USDA Forest Service, Forest Products Laboratory, 2021.
Used for: Gloss and clear finishes accentuating planer marks and raised grain; end grain about 100 times more porous than side grain.
- 11.
Wood Dust: Hazard Recognition. U.S. Department of Labor, Occupational Safety and Health Administration.
Used for: Wood dust's health effects, including respiratory effects and cancer.
- 12.
Reduce the Risk of Lead Exposure at Home. U.S. Environmental Protection Agency, 2026.
Used for: Refinishing old furniture as a source of lead exposure, and wetting before any unavoidable sanding of old paint.
About this guide
Written by BenchRoot Editorial. How BenchRoot sources, checks and corrects its pages is set out in the Editorial Policy. If something here is wrong or unclear, the contact page explains how to tell us.