Q & A: Avoiding Swirl Marks

Q & A: Avoiding
Swirl Marks

 

Q:

I just stained a tabletop and
found it covered with tiny swirl
marks from my random-orbital
sander.What did I do wrong?

A:

Swirl marks are inevitable. The
trick is to use a technique that minimizes
their prominence.

Try this: let the weight of the sander
do the work. Guide it, but don’t press
down. More pressure removes wood
faster, but it also leaves more swirls.
Second, use graduated sandpaper
grits. Start with 120 to
remove mill marks,
then move to 150, 180 and 220.Don’t skip grit intervals.
Swirl marks left by 120-grit paper, for
example,won’t be easy to remove with
180-grit paper.

Your final and most important step
is to hand sand with the same grit you
used last on your machine.By the time
you get to 220 grit, the swirl marks
will be faint, but hand sanding is the
only way you will get rid of them
entirely.

Set a work light on your bench and
shine it at a low angle across the
sanded surface. A quick wipe with
denatured alcohol will reveal
any lingering swirl marks.

This story originally appeared in American Woodworker September 2003, issue #102.

Purchase this back issue.