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How It Works—and What Goes Wrong
The pad of a random orbit sander moves in two ways: It wiggles in a tight orbital pattern while it rotates. This combined movement leaves a random pattern of scratches running in every direction, overlapping, intersecting and becoming practically invisible. But if you sand the wrong way, you’ll prevent the sander from working properly. You’ll get visible scratches, often in the form of long, spiraling swirls. You may not see these swirls on raw wood, but a coat of stain will highlight them.
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Go S-L-O-W
When you use a random orbit sander, it’s natural to scrub back and forth in a hurry. But that produces swirls. Slow down! The slower you go, the more random the scratches will be. It’s not easy, but train yourself to crawl along at a turtle’s pace—about 1 in. per second. To get a feel for that pace, try watching a stopwatch or a clock with a timer while you sand.
