Expert Answers: Smarter sanding

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This article is from Issue 78 of Woodcraft Magazine.

Q: Is there a proper way to sand wood to prepare it for a finish? At what grit should I stop?

A: The goal of sanding is to create a surface that is free of defects and smooth to the touch. There are different ways to get the job done, but for the sake of efficiency, I rely most on my random-orbit sander.

Choosing the right grit to start with depends on the condition of the wood. If you operate like I do, the last machine to touch the wood is usually a planer. In this case, I typically start with 80 grit, step up to 120, and stop at 180. Conventional wisdom advises against skipping grits, but as long as each new grit is removing the defects left by the previous one, I don’t think it’s necessary to sand more. Sanding technique is important. At each step, I sand in two directions: across the grain (remember it’s a random-orbit sander!) and with the grain. I find this method allows me to keep the sander moving at a pretty good speed (heat is the enemy of sandpaper) but still establish a uniform scratch pattern. On flat surfaces, such as drawer fronts and case sides, I’ll finish up by hand-sanding in the direction of the grain with final/finest grit.

Your choice of finish and desired sheen also affects the final grit. When using a penetrating finish, I’ll sand through 400 grit and then rub down the piece with 0000 steel wool. When using a film-building finish, you can continue sanding the fully-cured finish with even finer grits to achieve a higher polish.

—Chris Hedges, contributing editor


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