Woodworking Tips
Woodworking Tips Index
Sanding Tips, Part 3
Here's the third and final part of the sanding series. Today: When to Stop, and some Quick Tips.

When should you quit sanding? The answer depends on the finish. There are two questions to consider: Are you going to stain the wood? And what type of stain are you going to use? When using a pigment stain (as opposed to a dye), you have to keep a couple things in mind. First, how much you sand affects how dark the stain will end up. A stain sits in the pores and scratches (from the sand paper) of the wood. So the finer you sand, the fewer places there are for the stain to sit -- and the lighter the final color will be. Also keep this in mind. When you're going to stain a project, everything has to be sanded to the same grit. Otherwise the wood won't absorb the stain evenly (the exception is end grain, see Quick Tip #6 below).

Another factor that determines how fine you should sand is the finish you intend to use. The thicker the finish you're going to apply, the less you have to sand. Here's why:

With oil finishes (finishes that penetrate the wood and build almost no film at all), what you end up feeling is the wood, not the finish. So if you want the surface to feel smooth, you will need to sand the wood more. In this case, I would usually sand to about 220-grit. Then, for the first coat of finish, I'd sand it in wet with 320-grit sandpaper. This leaves the surface very smooth.

With a "film finish" like varnish, the finish needs to be smooth, not the wood. So sand the wood to about 120-grit or 150-grit. This may sound too coarse, but once the finish has built up on the surface, you won't be able to feel the wood anyway. In this case, to get a smooth surface, lightly sand the finish between coats.

1) Don't sand the wood like you scrub a floor. Use long even strokes. This way, you'll be sanding in a straight line with the grain, not going sideways across the grain.

2) Sand glued-up panels and large pieces before cutting them to final size. This keeps the thickness are the edges more consistent.

3) Don't sand up to the edge of a board with a power sander unless you want to round the edges slightly. Use a sanding block instead.

4) If you're sanding with 150-grit and you find a deep scratch, don't keep sanding at 150. Instead, switch a coarser grit to remove the scratch, and then work back up to 150 and continue.

5) If you've stained a project, be careful sanding between coats of finish. And avoid the edges if possible. It's too easy to cut through the finish and remove the stain.

6) To get the end grain of a workpiece to accept a stain the same as the face grain, sand it a couple of grits finer.

7) If you're using regular sandpaper on a palm sander, load four layers of paper on the sander at one time. Then rip off the top layer when it's worn.

8) To sand in tight spaces like corners, use sandpaper wrapped around the end of a dull chisel or putty knife.
Go to Tip #55

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