|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.
SANDING QUICK TIPS:
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
Go to Tip
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
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.