Nick from Rocky River Woodworks demonstrated the test featured in this video.
Every woodworker has faced the question of how far to push sanding before it stops making a real difference. Nick set out to answer this with a hands-on experiment, sanding a series of walnut blocks to different grits and finishing them identically to see where the improvements actually stop showing up.
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Setting Up the Experiment
Nick prepared several identical wood blocks and worked through a range of sandpaper grits, moving from the coarsest to the finest. Each block was sanded to a specific stopping point so the results could be compared side by side later.
Using a random orbital sander connected to a shop vac for dust extraction, he progressed methodically through the grits, sanding each section before moving on to the next. This approach kept the process consistent across every sample, which was key to making the comparison fair.
Applying a Consistent Finish
To keep variables to a minimum, Nick chose Danish oil as the finish for every block. He avoided stain entirely, wanting the test to isolate the effect of sanding grit rather than any color or pigment changes.
He also made a point of applying the finish the same way on each sample, using the same tools and technique. This consistency mattered because any variation in application could easily be mistaken for a difference caused by the sanding grit itself.
Comparing the Results
After letting the finish cure fully, Nick examined each block under different lighting conditions, including a ring light set to two different color temperatures. He evaluated both the feel of the surface and its visual appearance from multiple angles.
The block sanded only to the lowest grit was rough to the touch and showed clear swirl marks in the wood grain. Moving up through the middle grits brought gradual improvement, but the real turning point came when the surface reached a certain grit level, where both texture and appearance noticeably improved compared to the lower grits.
Beyond that point, Nick found the differences became much harder to detect. Comparing the mid-to-high grits side by side, he noted only minor variations in smoothness and almost no visible difference in the finished appearance.
Where the Returns Start to Diminish
Once he reached the higher end of the grit range, Nick struggled to feel or see any meaningful improvement at all. The texture felt nearly identical, and under close inspection with directional lighting, the finish looked the same regardless of whether the block had been sanded to a mid grit or the very highest grit tested.
He acknowledged that pushing to the highest grits could still be worthwhile for high-end or client work where every detail might be scrutinized. But for most everyday projects, he found that sanding to a moderate grit delivered results that were essentially indistinguishable from going much further.
What This Means for Everyday Projects
This test offers a practical takeaway for woodworkers who want to save time without sacrificing quality. Rather than assuming higher grit always equals a better result, it pays to test how far a particular wood and finish combination actually benefits from extra sanding.
Nick’s experiment suggests that once a surface reaches a certain smoothness, additional sanding effort may go unnoticed in the final product. Recognizing that point of diminishing returns can help woodworkers spend their time more efficiently, especially on projects where a flawless, magnified inspection isn’t necessary.
See Nick’s plans here: https://www.rockyriverwoodworks.com/plans-templates
Matt’s Take
These are my personal thoughts and tips based on my own experience in the shop. This section is not written, reviewed, or endorsed by the original creator of this project.
This kind of test lines up with what a lot of us find over time in the shop. Wood only holds so much finish, and once you close up the surface enough that stray scratches aren’t catching light, extra grits mostly just polish air. Walnut is a good candidate for this too since it’s a tighter-grained hardwood that doesn’t have huge pores to fill, so the sanding differences show up more clearly than they would on something like oak or ash.
One thing worth keeping in mind is that the “good enough” grit can shift depending on the finish you’re using. Danish oil and other penetrating oils tend to be forgiving, since they soak in and don’t sit on top the way a film finish does. If you’re spraying lacquer or laying down a poly, you might notice sanding marks telegraph through more easily, so it’s worth running your own version of this test with whatever finish you actually plan to use.
From a safety and technique standpoint, sanding dust from walnut can be more irritating to some people than lighter woods, so good dust collection or a mask is a smart move regardless of grit. Pairing a random orbital sander with a shop vac like Nick did is a great habit to build early since it keeps the work area cleaner and makes it easier to actually see your progress between grits.
At the end of the day, tests like this are a good reminder to slow down and evaluate your own results instead of chasing a number just because it’s the next one up on the pack of sandpaper.