WORKBENCH GUIDE
Sanding grit sequence before finishing
The right grits depend on the finish and on whether the wood is open- or closed-grained. A finish maker’s table, and why to stop where it says.
Grit by finish
General Finishes publishes grit sequences for preparing raw wood. The finest grit depends on the finish: stains need open pores to take colour, paint needs a slightly toothed surface, and closed-grain woods can be sanded finer than open-grain ones before a water-based stain.
| Finish | Grit sequence |
|---|---|
| Paint | 120, then 150 |
| Water-based stain, closed-grain wood | 150, then 220 |
| Water-based stain, open-grain wood | 120, 150, then 180 |
| Oil-based stain, closed-grain wood | No finer than 180 |
| Oil-based stain, open-grain wood | 120, 150, then 180 |
| Clear water-based topcoat | 120, then 150 or 220 |
| Clear oil-based topcoat | Up to 150 |
Open and closed grain
The Wood Handbook lists ash, hickory, oak and walnut among hardwoods with large vessels, and aspen, cherry and maple among those with small vessels; softwoods have no vessels. General Finishes groups cherry, pine, maple, birch and alder as closed-grain woods, and oak, ash, mahogany and parawood as open-grain woods.
Large vessels may need a filler for a smooth film finish. After filling and wiping off the excess, a light sanding usually comes before the finish (Wood Handbook, chapter 16).
Do not over-sand
General Finishes warns against over-sanding with the final grits: a surface that is too smooth can reduce stain absorption. This table follows its raw-wood sanding FAQ; follow the instructions for your specific finish if they differ, rather than automatically sanding finer.
Coarse paper has its own risk before gluing: the Wood Handbook shows that new 36-grit paper crushes several layers of surface cells. Planed surfaces are better for glue joints; use coarse grits only to remove defects, then work up to the final grit.
Raised grain and blemishes
Transparent finishes make blemishes more visible, so planer marks and raised grain should be removed before finishing. To deal with raised grain, wet the surface, let it dry and sand; one wetting is typically enough (Wood Handbook, chapter 16).
An oak side table with a water-based stain: 120, then 150, then 180 grit. A maple shelf with the same stain: 150, then 220.