Quick answer: Wet sanding is sanding with water (or a light oil or soapy water) on the surface. The liquid floats the dust away so the paper doesn't load, keeps the surface cool, and lets a fine grit leave a finer, more even scratch than the same paper used dry. It removes very little material, so you dry sand first to shape and level, then wet sand to remove the dry-sanding scratches and get an even, glossy-ready surface. Use waterproof silicon carbide paper, 400 grit and up for wood and finishes, 180–400 and up for metal, and 1000–2000 for automotive paint.
How wet sanding is different from dry sanding
| Dry sanding | Wet sanding | |
|---|---|---|
| Purpose | Remove stock, level and shape | Remove fine scratches, refine and even out the surface |
| Cut | Fast, aggressive | Slow, very light |
| Loading | Paper clogs with dust | Water carries dust away – paper stays sharp |
| Heat | Builds up, can soften finishes | Stays cool |
| Dust | Airborne | Almost none – a slurry you wipe up |
| Motion | Circles or random orbit | Straight, overlapping strokes with a light hand |
| Paper | Any | Waterproof (silicon carbide, latex or film backing) |
What you need
- Waterproof paper. Ordinary sandpaper falls apart when wet. Use wet/dry silicon carbide sheets – the black paper – or a sanding sponge for curves. Soak paper in water for 10–15 minutes before use so it's fully pliable.
- Water with a drop of dish soap as the lubricant. Soap helps the paper glide and stops particles sticking. For a glossier result on metal or finishes, a light oil or mineral spirits can be used instead.
- A sanding block for flat surfaces so you don't dig in with your fingertips.
- A bucket or spray bottle to keep the surface wet, and clean rags to wipe the slurry off and check your progress.
When to wet sand – by material
Wood and furniture
Wet sanding raw wood is unusual – water raises the grain – but wet sanding a finish is standard practice. Between coats of varnish, lacquer or polyurethane, and on the final coat, wet sanding with 400–600 grit levels dust nibs and brush marks without cutting through, and 1000–1500 gives a rubbed-out, satin-to-gloss surface. Use very little water on wood; it soaks in, and too much will swell the surface. The bonus for furniture in the house is that wet sanding makes almost no dust.
Metal
Wet sanding is how you take metal from a ground finish to a polished one. Start around 180 grit to remove the coarser scratches, move to 320, then 400 and finer, re-wetting constantly and changing direction 90 degrees at each grit so you can see when the previous scratches are gone. Follow with buffing compound for a mirror – see our polishing vs. buffing guide.
Automotive paint and clear coat
Car paint is where wet sanding earns its reputation. Wet sanding with 1000–2000 grit levels orange peel, dust and runs in fresh clear coat, and removes scratches from cured paint, before compounding and polishing bring the gloss back. Dry sanding here is far too aggressive. Our step-by-step wet sanding guide walks through the full process for paint.
Drywall and plaster
Wet sanding joint compound with a damp sponge knocks down ridges with no dust at all. It's slower than dry sanding but there's nothing to clean up afterward.
Grit guide for wet sanding
| Job | Start | Finish |
|---|---|---|
| Between finish coats on wood | 400 | 600 |
| Rubbing out a final wood finish | 600 | 1000–1500 |
| Metal, scratch removal to polish | 180–320 | 400–800, then buff |
| Fresh clear coat (orange peel, dust) | 1000–1500 | 2000, then compound |
| Scratch in cured paint | 1500–2000 | 2500–3000, then compound |
Move up in steps of no more than double the grit number, and never skip the compounding and polishing stage on paint – wet sanding leaves a dull, uniform haze that only polishing brings back to gloss.
Technique in four steps
- Dry sand first to shape, level and remove stock. Wet sanding won't do that job.
- Soak the paper, wet the surface, and sand in straight overlapping strokes with light pressure. Let the paper do the work.
- Keep it wet. If the slurry turns thick or the paper drags, add water.
- Wipe clean, dry, and inspect before moving to the next grit. When the previous grit's scratches are gone, move up.
Shop wet/dry sanding sheets in 60 to 2000 grit, or browse all polishing and finishing abrasives.
