Short answer: Match the grit to the job. Coarse grits remove old finish and deep scratches. Medium grits smooth the surface. Fine grits prepare the wood for stain or clear finish. The finest grits scuff a finish between coats.
Grit by job
- 40 to 60: very coarse. It removes a lot of wood quickly and is rarely right for furniture.
- 80: removing old finish or deep scratches on solid wood.
- 100 to 120: general preparation after stripping, and removing the scratches left by 80-grit paper.
- 150 to 180: the final grit before stain on most hardwoods.
- 180 to 220: the final grit before a clear finish. Use 220 on fine-grained woods such as maple and cherry.
- 220 to 320: scuff-sanding between coats of finish.
- 320 to 400: final sanding between coats, and removing dust nibs.
- 600 to 2000 (wet): rubbing out a cured finish to an even sheen.
Progression: don’t skip more than one step
Step through the grits in order, for example 80, then 120, then 150, then 180. Skipping grits feels faster, but coarse scratches take longer to remove than the time you save. Don’t go finer than you need, either. Finer is not always better, because very fine paper can make the wood harder for stain to penetrate.
Before stain
Stop at 150 to 180 on most hardwoods. If the wood is fine-grained, 220 may be right. Sanding much past 180 or 220 before stain can burnish the wood and make the stain come out lighter and patchy.
Sand end grain one grit finer than the face grain. This reduces how much stain end grain absorbs, which helps the finished color match.
Some guides suggest a finer final grit, such as 320, before stain. That can work with some film finishes, but it’s a judgment call. Test on a hidden area before you commit.
Between coats
Scuff-sand with 220 to 320 grit between coats of finish to give the next coat something to grip. Use 320 to 400 for the final light sanding, and wipe off the dust before the next coat. The same approach works between coats of paint, as covered in wood furniture painting techniques.
CAMI and FEPA grit labels
US sandpaper is often labeled by CAMI grit. European paper uses FEPA “P” grades. They match closely up to about 220, then diverge at higher grits. For example, CAMI 320 is roughly P400, and CAMI 400 is roughly P800. These are approximate, so check the label on the paper you buy.
Choosing the paper
- Aluminum oxide is the general-purpose wood abrasive.
- Silicon carbide suits finishes and wet sanding.
- Garnet cuts gently but wears out fast.
- Ceramic removes material quickly for heavy work.
- Stearated (no-load) paper resists clogging on finishes.
Change the paper when it stops cutting. Worn paper burnishes the surface instead of cutting it.
Technique
Sand with the grain. Use long, even strokes, and keep the sander moving so you don’t dig in. At the final grit, sand by hand with the grain to remove the swirl marks a random-orbit sander can leave. Wipe off dust between grits, so coarse particles don’t scratch the next stage.
For a broader look at prep, see how to restain wood furniture without stripping, which covers scuff-sanding a sealed finish.
Dust safety
Fine wood dust is a respiratory hazard. Wear an N95 or better, and use dust extraction if you can. Sand outdoors or in a well-ventilated room, and clean up dust afterward rather than sweeping it into the air.