Between polyurethane coats, 220–320 grit works for most jobs; shift to 400 grit for water-based or your last scuff.
Polyurethane can lay down slick and clear, then a single speck of dust lands and wrecks the finish. The fix isn’t more brushing. It’s a light scuff sand at the right grit, done at the right time.
You’ll get a straight grit answer, then a simple way to pick grit by finish type and coat stage. After that: a sanding routine that keeps the film intact and a troubleshooting chart for the usual headaches.
Grit choices at a glance for common polyurethane jobs
Use this table as your picker. Then use the steps below so you don’t sand too soon, press too hard, or trap dust under the next coat.
| Situation | Grit range | What you’re trying to do |
|---|---|---|
| First coat on bare wood (brushed oil-based poly) | 220–320 | Knock down raised grain and tiny hairs without cutting to bare wood |
| Between coats (most furniture, brushed oil-based) | 320 | Level dust nibs and leave fine scratches the next coat can grab |
| Between coats (water-based poly) | 320–400 | Smooth grain lift while keeping the finish clear |
| Spray polyurethane between coats | 220–320 | Flatten dry overspray and dry “orange peel” texture |
| Tabletops and other touch-heavy surfaces | 320–400 | Even out the film so it feels slick after the next coat cures |
| Floors (between coats after screen or pad) | 220–320 | Scuff the sheen and shave off grit bumps so coats bond |
| Last scuff before the final coat | 400 | Remove last nibs while keeping enough tooth for the last coat |
| After the final coat cures (optional rub-out) | 600+ | Refine feel and sheen before polishing |
What Grit To Sand In Between Polyurethane Coats?
If you’re asking what grit to sand in between polyurethane coats?, start with 320 grit for most projects. Use 220 grit when you need more bite to level rough spots, and use 400 grit for a gentler scuff on water-based coats or right before the last coat.
Between coats, you’re not shaping wood. You’re shaving tiny bumps and leaving a fine scratch pattern so the next coat bonds well and levels out.
Choosing grit between polyurethane coats by finish type and coat stage
Oil-based polyurethane
Oil-based poly often dries slower and builds a tougher film. Many labels call for a light sand before recoating. Minwax’s fast-drying polyurethane data sheet says to lightly sand with 220 grit after it dries, then remove dust before the next coat. You can check that wording on the Minwax® Fast-Drying Polyurethane product data sheet.
In practice, 320 grit is the calm middle ground for most oil-based coats. It’s fine enough for clear finishes, yet it still cuts nibs fast.
Water-based polyurethane
Water-based poly can raise the grain more on the first coat, and it can feel “fuzzy” even when the film looks clean. A 320–400 grit sand between coats keeps the surface from feeling prickly without hazing the finish.
General Finishes notes sanding between coats with a 220 sanding pad or 400-grit sandpaper on many topcoats, with higher grits used for a smoother feel. That’s on their General Finishes finish sanding video page.
Spray polyurethane
Spray poly can dry with a fine texture from overspray. If it feels like sandpaper after it dries, scuff with 220–320 until it feels even, then lay the next coat lighter and wetter so it flows out.
A sanding routine that keeps the polyurethane film intact
The goal is a dull, evenly scuffed surface with no shiny pits and no bare wood peeking through.
Step 1: wait until the coat is sand-ready
Dry-to-touch isn’t the same as sand-ready. If the paper clogs fast or you feel the finish balling up, stop. Give it more time. A coat that sands into a fine powder is ready.
Step 2: match the sanding tool to the surface
- Flat panels: Wrap paper around a sanding block so pressure stays even.
- Curves and profiles: Use a flexible sanding pad so you don’t cut through edges.
- Floors: A screen, pad, or pole sander keeps the scuff even across a big area.
Step 3: sand light, then stop
Use a feather touch. You’re shaving high spots, not thinning the whole coat. Work with the grain when you can. If you’re using a random-orbit sander on a tabletop, keep it moving and don’t linger on corners.
Quick test: if the surface feels smooth and the sheen looks evenly dulled, you’re done.
Step 4: clear dust before you recoat
Dust left behind turns into bumps trapped under the next coat. Vacuum first. Then wipe with a clean, slightly damp microfiber cloth, or use a tack cloth made for finishes. Let the surface dry before you coat again.
When 220 grit makes sense, and when it’s too aggressive
220 grit levels roughness fast. Use it when your first coat raised grain hard, when you’ve got runs to flatten, or when spray texture feels pebbly.
But 220 can leave scratches that show under glossy coats, especially on dark stain. If you start with 220, follow it with a quick pass of 320 before recoating.
When 320 grit is the safe default
For most furniture builds and trim work, 320 grit is the “no drama” pick. It knocks down dust nibs quickly and the scratches are fine enough to vanish once the next coat levels out.
When 400 grit earns its spot
400 grit is for light scuffing when your coat already feels smooth and you just want adhesion. It fits water-based poly and it’s handy as your last scuff before the final coat on a tabletop.
One catch: 400 doesn’t level bumps as fast. If you can feel nibs with your fingertips, start with 320, then finish with 400 using a couple easy strokes.
Edge and detail work without sanding through
Corners and edges are where coats are thinnest. If you sand them like a flat panel, you’ll hit bare wood fast, then you’re stuck spot-coating and chasing color shifts.
Try this instead:
- Fold the paper and pinch it lightly, instead of pressing a block hard onto an edge.
- Make two or three passes, then stop and check.
- On sharp edges, switch to a worn sanding pad. A broken-in pad cuts softer.
Cleaning between coats without leaving residue
After sanding, you want zero grit on the surface. A shop vacuum with a soft brush head gets most of it. A microfiber wipe grabs what the vacuum misses. If you use a tack cloth, use a light touch so you don’t smear residue onto the film.
Skip household cleaners. Many leave surfactants that can cause fisheyes. Keep the routine boring: vacuum, wipe, dry, coat.
Dry sanding and wet sanding between coats
Between coats, dry scuff sanding is usually the cleanest move. It gives the next coat tooth. Use wet/dry paper dry; a fine synthetic pad works on curves.
Wet sanding has a place, but save it for later. Do it after the final coat has cured, when you’re chasing a softer feel or a flatter sheen. If you wet sand too early, you can trap moisture under a new coat and get cloudy spots.
- Wait until the finish sands to powder and feels hard to a fingernail.
- Use 600 grit or finer with a light lubricant like water with a drop of dish soap.
- Wipe dry, then let the surface sit until it’s bone-dry before any polish.
Common sanding and recoating problems and quick fixes
Most polyurethane “mysteries” come down to sanding too soon, sanding too hard, or coating over dust. Use this table to spot what’s going on and fix it fast.
| What you see | Likely cause | What to do next |
|---|---|---|
| Sandpaper gums up right away | Coat isn’t sand-ready yet | Stop, wait longer, then try 320 again when it powders |
| White, hazy patches after sanding | Too much pressure or sanding too fine too soon | Wipe clean, recoat thin, then scuff with 320 on the next round |
| Shiny low spots that won’t dull | Uneven film thickness or missed areas | Scuff the surrounding area with 320 and recoat to level the sheen |
| Swirl marks visible in raking light | Random-orbit sanding with grit too coarse | Hand-sand with the grain using 320, then recoat |
| Edges turn darker or go bare | Sanded through the film | Feather the spot with 320, recoat, and sand edges lighter next time |
| Dust bumps show up again after recoating | Dust left on the surface | Vacuum and wipe more carefully before the next coat |
| Coats peel or scratch off too easily | Missed scuff between coats or recoat window missed | Scuff the whole surface with 220–320 and lay a fresh coat |
Mini checklist before you lay the next coat
This is the fast run-through I use so I don’t second-guess myself mid-coat.
- Coat sands to a fine powder, not rubbery crumbs.
- Surface is evenly dull with no glossy pits.
- Edges feel smooth and aren’t cut through.
- Dust is gone: vacuum first, microfiber wipe second.
- Brush, pad, or sprayer is clean and dry.
- Next coat goes on thin and even.
So, what grit should you grab right now?
If you want one pick for the shop drawer, grab 320 grit and a soft sanding pad. Keep 220 for rough first coats and spray texture. Keep 400 for water-based coats and that last scuff that makes a tabletop feel slick.
And if you circle back to the original question—what grit to sand in between polyurethane coats?—you’ll know it’s about reading the coat in front of you, then sanding just enough to make the next coat bond clean and level.