Sandpaper Company Guide to Selecting the Perfect Grit for Any Surface

Ever stared at a wall of sandpaper grits and wondered which one won’t ruin your project? You’re not alone. In this guide, we break down exactly how to match grit to surface—so you stop second-guessing and start sanding smart. Brought to you by SHENZHEN SUN ABRASIVES, a company that lives and breathes abrasives.

What Those Sandpaper Numbers Actually Mean for Your Project

The number on a sheet of sandpaper refers to its grit, and that little digit tells you how aggressive or gentle the abrasive will be. Lower numbers—think 40, 60, or 80—mean bigger, rougher particles that chew through material fast but leave visible scratches behind. Higher numbers, like 220, 320, or 400, pack finer particles that smooth surfaces to a near-polished feel. If you grab a 60-grit disc to knock down a rough edge, expect quick work and a coarse finish; switch to 180 or higher when you want to erase those marks and prep for paint or stain.

The trick isn't memorizing a chart, it's matching the grit to the stage of your project. Start with a coarse grit to level uneven wood, strip old finish, or round a sharp corner. Then work your way up through the middle range—100 to 150—to blend the surface. Finally, finish with 180 to 220 for a smooth base that accepts finish evenly. If you jump straight from 60 to 220, you'll spend forever trying to remove deep scratches the fine grit can't touch. Different materials also respond differently: softwoods clog finer paper faster, while metal often benefits from a few extra intermediate steps.

A common mistake is assuming higher numbers always produce better results. Fine grits are useless for heavy material removal; they just glide over bumps without cutting them down. Another point people overlook is that the backing and abrasive type matter as much as the number—cheap aluminum oxide wears out quickly, while ceramic or silicon carbide holds up longer under pressure. Before committing to a full project, sand a small hidden area and feel the result. That quick test beats any numbered label and tells you exactly what your hands are in for.

Wood Sanding Without the Guesswork: A Grit Roadmap

Sanding works best when you stop treating grit numbers as a countdown and start seeing them as a sequence of scratch-depth reductions. For raw stock or old finish removal, start at 80 grit and don’t move on until the surface shows a uniform scratch pattern with no shiny low spots. If a board still has mill marks or tear-out, dropping to 60 is faster than pressing harder with 80—pressure just loads the paper and burns the wood.

From there, double the grit each pass: 80 to 120 to 180 to 220. The jump from 120 to 150 is often wasted time because 150 only polishes the tops of the scratches left by 120 without cutting them down. On open-pored woods like oak or ash, stop at 180 if you plan to stain; going to 240 can burnish the surface and reduce stain penetration. For film finishes on tight-grained woods like maple or cherry, 220 is usually the stopping point before a coat, and between coats use 320 or 400 just to knock off dust nibs.

The real guesswork disappears when you use raking light and a pencil line. Draw a light scribble across the board after each grit, and sand only until the mark is gone. That tells you the previous scratches are fully leveled without over-sanding. Wipe the surface with a damp cloth and let it dry before the final pass—this raises the grain so the last sanding doesn’t get undone the moment finish hits the wood.

Metalwork Grit Choices That Prevent Scratches You Can’t Undo

Once a deep scratch bites into a metal surface, no amount of polishing will fully erase it without removing surrounding material. The mistake usually happens long before the final polish—when you jump from a coarse grit to a fine one too quickly. Those fine abrasive particles simply skate over the deep grooves, leaving what looks like a smooth finish until the light hits it from the wrong angle.

A safer path is to treat grit progression as a stairway, not a leap. If you start with 80 grit to shape or remove mill scale, don't grab 220 next. Step through 120 or 150 first. Each jump should reduce the previous scratch depth by roughly half. For soft metals like aluminum, even smaller increments help because the material smears easily and can hide damage until you anodize or clear-coat.

I keep a written sequence taped inside my abrasive drawer: 80, 120, 180, 240, 320, 400, then wet sanding with 600 and up. Before moving to the next grit, I wipe the surface with a rag and look at it under a raking light. If the previous scratch pattern is still visible, I stay on the current grit a bit longer. It's slow, but it beats ruining a part in the last fifteen minutes of a project.

Removing Paint or Varnish? Start Here, Not with 220

If the surface still has a solid film of old paint or varnish, grabbing a sheet of 220-grit sandpaper will waste your afternoon. That fine grit is meant for smoothing between finish coats, not for cutting through built-up layers. It loads up almost immediately, glazes over the finish, and leaves you rubbing the same spot while the coating stays stubbornly put.

The better first move depends on what you are dealing with. Thick, alligatored paint or a glossy varnish usually responds fastest to a chemical stripper. Brush on a generous coat, give it time to bubble, then lift the sludge with a plastic scraper. If you would rather stay dry, a heat gun and a pull scraper work well for oil-based paints, but keep the gun moving and have a respirator handy for lead-era layers.

For thin, worn finishes where you just need to knock down the surface and create a key for new paint, start with 120-grit or 150-grit instead. That is coarse enough to bite through the old sheen without clogging as fast. Only after the old color or gloss is gone do you step up to 220-grit for final smoothing before priming.

The Wet vs. Dry Sanding Grit Divide Nobody Explains

Most people assume a P1000 grit works the same whether you sand wet or dry, but the two methods live in different worlds. Under dry sanding, the grit loads up, the paper runs hot, and the abrasive eventually skates over the surface rather than cutting it. Add water and the slurry gets flushed away, so the same grit keeps biting and leaves a much more even scratch pattern. That alone makes a wet-sanded P1000 feel closer to a dry P1200 or finer.

The divide goes deeper than just water, though. Typical wet/dry sheets are made with silicon carbide on a waterproof backing, while many dry-only papers use aluminum oxide. Silicon carbide fractures into sharper edges under light pressure, slicing more like a chisel, whereas aluminum oxide tends to round over and plow. So the grit number on the package is only half the story: the abrasive type and binder change how deep those scratches actually go.

If you're moving from dry to wet sanding, don't grab the same grit and expect an identical result. Start one step coarser than your dry routine, use light, consistent pressure, and keep the surface flushed so the slurry doesn't build up. Test on a hidden corner first. Once you see how the finish shifts, you'll understand why wet and dry grit charts never really line up.

When to Jump Two Grits (and When to Never Skip One)

There's a persistent rule in the shop that you should move through every grit when sanding wood, no exceptions. That's decent advice if you're starting from rough lumber or removing planer marks, because each step clears the scratches left by the previous one. But the rule gets stretched thin once the surface is already flat and you're just chasing a smoother feel. In those cases, jumping two grits, say from 120 straight to 180, won't leave deeper grooves behind as long as the 120 scratches are fully gone before you move on. The real question isn't the number on the paper; it's whether the previous grit did its job completely.

But there are times when skipping even a single grit is a mistake. If you're working on a dense hardwood like maple or cherry and plan to apply a clear finish, the scratches you thought were gone will reappear under the first coat of oil or lacquer. The same holds when you're sanding end grain or curved profiles, where it's easy to miss spots while moving too fast. For these situations, stepping through every grit from 100 up to 220 or 240 gives you a visual checkpoint at each stage. If the surface doesn't look uniformly dull after the 150 pass, you know you haven't finished with 120 yet. That confidence is worth the extra sheets of sandpaper.

FAQ

Conclusion

Sandpaper grit numbers work backward from intuition: lower numbers mean coarser abrasive, higher numbers mean finer polish. For wood, you rarely need anything below 80 unless you're dealing with deep gouges or heavy paint buildup. A safe progression runs 80, 120, 180, then 220 before stain or sealer. If you skip from 80 straight to 220, the finish will highlight every scratch you thought you removed. Metal demands even more patience. Starting with 60 or 80 on steel or aluminum can carve grooves that are nearly impossible to sand out, so most metalwork begins at 120 and steps up gradually through 180, 240, and 320 before any buffing. This keeps the surface from bearing permanent scars that show up under paint or clear coat.

For stripping paint or varnish, starting with 220 is a common mistake. That fine grit loads up in seconds and mostly polishes the old coating instead of cutting through it. Begin with 60 or 80 grit to break the surface, then step to 120 and 150 to remove leftover residue before final prep. The wet versus dry question also trips up many DIYers. Dry sanding works for most wood and general paint prep, but wet sanding with 400 to 2000 grit is non-negotiable for automotive clear coats, lacquer, and polished metal because the water keeps the paper from clogging and floats away debris. When moving through grits, never skip more than one step at a time on bare material. Going from 120 to 180 is fine; jumping from 120 to 320 leaves scratches that later stages can't fully erase. The exception is when the surface is already smooth and you're only refining an existing finish, in which case leaping two grits is usually safe.