Orbital sander: what it does and when to reach for it

Learn what an orbital sander does, when to use one, and how to sand flat surfaces without leaving marks.

OS-01Know what the tool is forAn orbital sander is a power tool that moves a sheet of sandpaper in tiny circles very fast, smoothing wood or old paint without leaving the long scratches you get from sanding by hand. Reach for it when you have a flat area bigger than a sheet of A4 paper - a tabletop, a door, a skirting board length before fitting. For small fiddly bits, corners, or curved mouldings, hand sanding still works better because the sander cannot get into tight spots.

OS-02Fit the sandpaper disc correctlyMost orbital sanders have a flat pad on the base covered in a hook-and-loop surface (like Velcro) that grips a matching sandpaper disc. Line up the holes in the disc with the holes in the pad - these let dust get sucked through into the dust bag. Press the disc down firmly all over so it sits flat with no wrinkles; a loose or wrinkled disc wears out fast and sands unevenly.

1 pack · Sanding discs, assorted grit pack

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OS-03Pick the right grit for the jobGrit is the number printed on the back of the disc, and it tells you how rough or fine the sandpaper is - low numbers like 40 or 60 are coarse and remove material fast, high numbers like 180 or 240 are fine and just smooth the surface. Start with a coarser grit only if you are removing old paint or levelling rough wood, then move up through the numbers to finish fine. Beginners often use one grit for everything and end up either sanding forever or leaving deep scratches that show through paint.

OS-04Hold it and switch it on properlyHold the sander with both hands where the grips are moulded, and rest the pad flat on the surface before you switch it on. Never switch it on in mid-air and then bring it down - it can skate sideways and mark the wood or your hand. Let the sander reach full speed for a second before you start moving it.

OS-05Move it slowly, let the tool do the workKeep the pad flat and move it in slow, overlapping straight lines or gentle circles, using only light pressure - the weight of the sander is usually enough. Pressing hard does not sand faster; it just overheats the paper and can dig a shallow dip into soft wood. The mistake almost every beginner makes is stopping still in one spot, even for a second, which grinds a visible hollow that is very hard to fix afterwards.

OS-06Protect yourself from the dustSanding throws fine dust into the air even with a dust bag fitted, and it is bad to breathe in over time. Wear a proper dust mask (not just a thin paper one) and safety glasses, and work with a window open or outdoors if you can. Empty the dust bag often - a full bag stops the sander collecting dust properly and it ends up back on your surface and in the air.

1 each · Disposable dust mask (FFP2 or better)

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OS-07Check you've done it rightRun your flat hand over the surface with your eyes closed - you should feel smooth, even wood with no ridges, no shiny patches of old finish left, and no dips. Wipe the dust off with a dry cloth and look across the surface at an angle in good light; swirl marks or a slightly darker hollow patch mean you lingered too long in one spot. If it still feels rough in places, go back over just that area with the same grit before moving up to a finer one.

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