When using a finish that calls for only sanding up to 150 grit (Waterlox in this instance), how do you eliminate swirl marks from a random orbit sander?
Swirl marks and finishes calling for coarse sanding
- Thread starter Ericlassiter18
- Start date
Did you raise the grain in between grits? I have found by wiping the wood with a damp shop rag helps to raise the grain and also get rid of the more course grit from the last grit before you move higher. Let the wood dry to the touch before sanding at the higher grit. You may be putting too much pressure down on the orbital sander and may want to only sand with the grain. Hope some of this is helpful.
With an electric ROS, start and stop it off the surface.
With a pneumatic ROS [also called a DA (dual-action) sander], start and stop on the surface.
If you have an electric ROS in which the anti-overspin function is not working, treat it like a pneumatic ROS.
As stated already, too much pressure will aggravate the situation, as can resin build-up on the paper
With a pneumatic ROS [also called a DA (dual-action) sander], start and stop on the surface.
If you have an electric ROS in which the anti-overspin function is not working, treat it like a pneumatic ROS.
As stated already, too much pressure will aggravate the situation, as can resin build-up on the paper
I had only been doing this for water based finishes, but I’ll give it a shot this time around
The big secret for ROS or vibrator sanders is to move the sander at a rate of one inch per second. So set off a 12" distance, look at your watch, and move your finger at a pace that will result in 12 seconds. A few practice tries and you'll have it.
Yes, to the above responses, don't press down. Let the sander do the work. That's what it is designed for.
A good belt sander with a good belt (no tape joint) will also work well.
Yes, to the above responses, don't press down. Let the sander do the work. That's what it is designed for.
A good belt sander with a good belt (no tape joint) will also work well.
Richard, thank you for the feedback...I was not aware of the "standard". My approach has been to sand to the desired end-point, apply finish, and then repeat as needed.
Another suggestion is to not use full power on your dust extraction. You can create a variable leak between the vac and the sander with a 3/4" hole drilled into an inline connector. Cover with masking tape when you need the full power. This lightens the downforce on the abrasive creating less swirls and also pills/boogers of finish on the paper if you are stripping a piece. I use a wye from Fein with a cover over the unused side of the wye.
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I work almost exclusively in QSWO and have found that anything over 150 grit causes the wood to not hold stain as much as I would like (can't get the wood dark enough), so I have become very good at getting a good finish with low grits. Don't press down, change paper often and get a good form of raking light to help find any swirl marks.
This may explain my continuing swirl mark issue. I don't press at all but still have marks. I noticed they were all small diameter which implies they come from the center of the wheel. some ROS have a gap in the center but mine didn't. cut one into mine which seemed to help. But over suctioning explains the original problem.
Thanks,
pas
Hate to be the one to kick sand in your face, but... Card Scraper.
I have not tried this yet, but I saw a video where they recommended sanding up to 220 with the ROS, then coming back with 150 and sanding by hand with light strokes.
Swirls are caused by (in order)
1) moving the sander too quickly,
2) too much pressure,
3) too high a speed,
4) somewhat dependent on quality of sander,
5) not changing paper frequently enough.
Been doing this 40 years. FWIW if you don't want swirls, do the final sanding by hand.
I think hand sanding is the red headed step child for a lot of ww'ers. You'll be surprised how fast it is, and how safe it is, particularly around edges.
We don't need machines for everything!!!
1) moving the sander too quickly,
2) too much pressure,
3) too high a speed,
4) somewhat dependent on quality of sander,
5) not changing paper frequently enough.
Been doing this 40 years. FWIW if you don't want swirls, do the final sanding by hand.
I think hand sanding is the red headed step child for a lot of ww'ers. You'll be surprised how fast it is, and how safe it is, particularly around edges.
We don't need machines for everything!!!
Simple answer: ROS gets you close. Always finish sand with the grain by hand. I sand a couple grits finer with the ROS and then it is really easy and quick by hand. I also think some of those course grit recommendations are way out of line. They must be hold over from worn out flint paper. Even for a BLO/wax finish, I will hand sand no rougher than 220 using 3M purple sheets. Natural wood you can get away courser, if staining, go finer. The walnut table I just finished I did finer and it came out great. 400 mesh and 220 hand. It also depends slightly on the wood.
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