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Q & A: Avoiding Swirl Marks


Q & A: Avoiding Swirl Marks



I just stained a tabletop and found it covered with tiny swirl marks from my random-orbital sander.What did I do wrong?


Swirl marks are inevitable. The trick is to use a technique that minimizes their prominence.

Try this: let the weight of the sander do the work. Guide it, but don’t press down. More pressure removes wood faster, but it also leaves more swirls. Second, use graduated sandpaper grits. Start with 120 to remove mill marks, then move to 150, 180 and 220.Don’t skip grit intervals. Swirl marks left by 120-grit paper, for example,won’t be easy to remove with 180-grit paper.

Your final and most important step is to hand sand with the same grit you used last on your machine.By the time you get to 220 grit, the swirl marks will be faint, but hand sanding is the only way you will get rid of them entirely.

Set a work light on your bench and shine it at a low angle across the sanded surface. A quick wipe with denatured alcohol will reveal any lingering swirl marks.

This story originally appeared in American Woodworker September 2003, issue #102.

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