Troubleshooting Sandpaper Scratch Marks

Sandpaper choices and sander settings both play a role in swirl marks created by small wood slivers that stick to the sandpaper. May 27, 2014

I finally bought a Festool sander after years of using everything else. So far, I'm not quite as enthusiastic about it as all the reviews I've read on them. In fact we changed back to a Porter Cable to remove the horrible swirl marks left by the Festool.

The problem is this. The Festool paper is holding slivers of wood and scratching the surface terribly. This happens after we raise the grain. All of the small slivers just seem to stick to the paper and won't come off unless you physically remove them. Has anyone had this problem and found a remedy?

Forum Responses
(Cabinetmaking Forum)
From contributor M:
I'm not sure about the "holding slivers" part, but I had a similar experience going from PC to Festool 5" sanders: lots of swirl. The solution for me was to form my own opinions of what the different types of paper are good for. In general, I've found that rubin paper sands coarse. So if you want a P120 type finish, then sand to p150. Brilliant sands more like the 3m Stickits that I had been using on the PCs on bare hardwood, so if I'm sanding oak for stain or cherry, I'll switch to Brilliant at P120 to get rid of the swirls. Good extraction; not good on paper, nor on the heat buildup that kills the hook on the pad.

From contributor X:
Also, if you have an extractor with variable speed (like the Festool), then turn it way down for sanding. Some of the smaller sanders like the ETS125 need to be turned down too close to the slowest speed. Too much vacuum can be as bad as not enough. I have been using the Rotex 125 with 120 grit to get the defects off from the widebelt sander, then finish up with the ETS125 with 150 grit rubins. It's nice having dedicated sanders, so you don't have to change paper back and forth.

From contributor M:
Another small note: I really have no idea what sanding process you are referring to. Raising the grain seems to suggest sanding sealer, but slivers of wood suggest bare wood. I do remember once in middle school shop class being instructed to spray my little duck cut-out with water to raise the grain before sanding, but I'd never consider doing such a thing now. So what is it? And what sanders/paper are you using?

From the original questioner:
This is sanding bare wood prior to finishing. I always raise the grain by wiping the piece down with a damp sponge, let it dry and sand away the swollen fibers. It eliminates any possibility of grain raising during the finishing process, helps bring unwanted scratches to the surface, and gives you a better finish. I think your shop teacher was onto something.

At any rate, I'm using rubin paper 120, 180 grit. When you raise the grain, it brings loose fibers to the surface. When they are sanded off with the rubin paper, they become lodged in the paper, causing swirl marks. Mirka garnet paper does not do this. I will probably try some brilliant paper to see how it does.

Sanding schedule is as follows: widebelt 120 grit, ROS 120, raise grain, ROS 150, 180. This particular job is red oak.

From contributor M:
Thanks. Learn something new, or old, every day. My guess is that the brilliant will work better for you, but your problem might have something to do with the extra coarseness of the FT paper. Perhaps raising after p150 would relate better to your process with Mirka paper.