How to Sand Ash Wood: Grit Sequence & Grain Direction Guide

Ash sands differently than a lot of the woods you might be used to. It has a straight, open, ring-porous grain structure similar to oak, which means cross-grain scratches, skipped grits, and swirl marks show up more obviously once a finish goes on. Getting a smooth result on ash comes down to four things: the right grit sequence, sanding with the grain instead of across it, a final hand pass to catch what a power sander leaves behind, and knowing when a grain filler is worth using. Here is how to do each one correctly.

Why Ash Wood Sands Differently Than Other Species

Ash is a ring-porous hardwood, which means the large early-wood pores that form each growth ring stay open on the sanded surface instead of collapsing shut the way they do in a tight-grained wood like maple or cherry. Oak has the same structural trait, and the two species sand and finish in a similar way for that reason. The practical effect is that any sanding mistake, a stray cross-grain scratch, a missed grit step, or a swirl mark from a random orbital sander, gets trapped right along the open grain line and becomes far more visible once stain or a film finish is applied and the pores catch the pigment or the light differently than the surrounding wood. That is also why ash has a reputation for blotching under stain: the density varies slightly between the porous early-wood bands and the denser late-wood bands, so the wood absorbs stain unevenly if it is not prepped correctly.

Tools and Sandpaper You Need

For most ash projects, a random orbital sander handles the flat surfaces and a sanding block or folded sheet handles edges, corners, and anywhere the sander’s round pad cannot reach cleanly. Keep a supply of sandpaper in 80, 120, 150, and 220 grit on hand, plus a few sheets of 320 if you plan to sand between finish coats. A stiff-bristle brush and a tack cloth or vacuum with a brush attachment matter more on ash than on a closed-grain wood, since dust that settles into the open pores and doesn’t get cleared out before the next grit will just get dragged around and create fine scratches instead of being sanded away.

The Right Grit Sequence for Ash: 80, 120, 150, 220

Start at 80 grit only if the ash still has mill marks, an old finish, or visible surface defects to remove. If the board is already reasonably flat and clean, 100 or 120 is a safer starting point, since ash’s open grain makes it easy for an 80-grit pass to leave scratches that the next grit up struggles to erase. From there, move to 120, then 150, then finish at 220. Skipping a step, going straight from 80 to 220, for example, is the single most common cause of a blotchy or streaky finish on ash, because the coarser scratches from the lower grit are still sitting in the open pores even though the surface feels smooth to the touch. Run each grit until the scratch pattern from the previous grit is gone before moving on, and wipe the dust off between every grit change so you can actually see what you’re sanding.

Always Sand With the Grain, Not Across It

This matters on every wood, but it matters more on ash because of that open, ring-porous structure. A cross-grain scratch on a tight-grained wood like maple can often be sanded out or at least minimized before finishing. On ash, a cross-grain scratch cuts directly across the open pore lines, and once stain or an oil finish goes on, that scratch reads as a visible dark or light line running the wrong direction against the grain pattern, and it will not sand out without going back several grits. Keep your sander or sanding block moving in long strokes parallel to the grain direction, not in circles and not diagonally, even though a random orbital sander’s spinning pad technically removes material in every direction at once. The orbital motion is fine for stock removal; your feed direction along the board is what determines whether the final scratch pattern lines up with the grain.

Finish With a Light Hand-Sanding Pass

Even a well-controlled random orbital sander leaves faint circular swirl marks in the surface, they’re usually invisible to the eye on bare wood but become obvious once a finish is applied and raking light hits the surface. After your last power-sanded grit, typically 220, switch to a sanding block or folded sheet of the same grit and hand-sand the entire surface in long strokes with the grain. This final pass does not need to remove much material, its job is to erase the last of the circular swirl pattern and true up the scratch direction to run with the grain everywhere, including in spots the sander’s pad shape couldn’t fully reach flat, like near edges and inside corners. Skipping this step is a common reason a sanding job that looked perfectly smooth in the shop suddenly shows a faint swirl pattern once the first coat of finish goes on.

Using Grain Filler for a Glass-Smooth Finish (Optional)

Because ash’s pores stay open even after 220-grit sanding, the surface will still have a faintly textured, slightly rough-to-the-touch feel under a thin finish like oil or wiping varnish. That texture is part of ash’s natural character, and plenty of furniture and cutting boards look great left that way. If you want a fully smooth, glass-like surface instead, a paste grain filler applied after your final sanding pass and before finishing is the way to get there. Wipe or brush the filler on, let it start to haze over per the product’s instructions, then squeegee off the excess across the grain and let it cure fully before a very light 220-grit pass and your first coat of finish. Grain filler is entirely optional, it adds a step and, if tinted, changes the look of the open grain, so treat it as a design choice rather than a mandatory part of sanding ash.

Preventing Blotchy Stain on Ash

If you plan to stain rather than use a clear or oil finish, sanding alone will not fully prevent blotching on ash, the density variation between early-wood and late-wood bands is what causes it, and that variation is part of the wood, not a sanding defect. A pre-stain wood conditioner applied 15 to 30 minutes before staining partially seals the denser areas so they absorb stain at closer to the same rate as the more porous bands. A gel stain is another option, since it sits on top of the surface rather than soaking in unevenly, which makes it more forgiving on ring-porous woods like ash and oak. Either approach works better than trying to compensate with extra sanding, since the blotching is a density issue, not a smoothness issue.

Common Sanding Mistakes to Avoid

• Skipping grits, jumping from 80 straight to 220 leaves earlier scratch patterns trapped in the open pores.
• Sanding across the grain, even briefly to speed up stock removal, since the resulting cross-grain scratches are much harder to remove on ash than on a tight-grained wood.
• Not clearing dust between grit changes, which lets fine grit particles drag across the surface and create random scratches.
• Skipping the final hand-sanding pass and finishing directly off the power sander, which leaves circular swirl marks visible under the finish.
• Over-sanding trying to eliminate the open-pore texture entirely with sandpaper alone, when a grain filler is the actual tool for that job.

Frequently Asked Questions

What grit should I start with when sanding ash wood?

Start at 80 grit only if the board has mill marks, an old finish, or visible defects to remove. If the surface is already reasonably flat and clean, start at 100 or 120 instead, then work up through 150 and finish at 220. Starting coarser than necessary on ash just creates deeper scratches in the open grain that take longer to sand out.

Why does ash wood scratch more easily than other woods when sanded across the grain?

Ash has a straight, open, ring-porous grain structure similar to oak. Cross-grain scratches cut directly across those open pore lines, and once a finish is applied, the scratch reads as an obvious line running the wrong direction against the grain pattern. On tighter-grained woods that same scratch is often far less noticeable.

Do I need to use a grain filler on ash wood?

No, it’s optional. Ash’s open pores stay slightly textured even after a full 80 to 220 grit sanding sequence, which is part of the wood’s natural character and looks fine under an oil or wiping-varnish finish. Grain filler is only necessary if you specifically want a fully smooth, glass-like surface instead of that natural open-pore texture.

Conclusion

Sanding ash wood well comes down to respecting its open, ring-porous grain: don’t skip grits in the 80 to 220 sequence, always sand and feed with the grain rather than across it, finish with a light hand pass to erase power-sander swirl marks, and decide up front whether you want the natural open-pore texture or a filled, glass-smooth surface. If you’re planning a specific build with ash, our ash wood project ideas guide covers beginner-friendly projects and the finishing steps that pair with the sanding techniques above.