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post #1 of 10 Old 10-19-2017, 05:04 PM Thread Starter
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Sanding Problem

I'm new to the Forum. I keep having a problem with my Orbital and 1/4 sheet sanders. I keep getting little swirls on the wood work and can't see it until I start to put on stain. Is there something wrong with my sander or am I doing something wrong?
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post #2 of 10 Old 10-19-2017, 05:34 PM
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Welcome to the forum

Usually what causes that is going to a finer grit too soon, my rule of thumb is not to use any thing finer than 50 grit (or as close as you can get to it) as you work up to finer grit, IE 100-150-180-220-280-320-400

When you get to the super finer grit you can go 100 grit or more but the course grit you have to move up slower

Another thing you can do is wipe the project with mineral spirits so see if you have any swirl marks before you stain the wood, much easier fto fix
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post #3 of 10 Old 10-19-2017, 06:02 PM
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Yeah, that looks exactly like my work does when I go straight from 60 to 240 grit. If you don't have the intermediary grits, you have to spend a LOT of time with the finer discs to get the rougher swirls out.
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post #4 of 10 Old 10-19-2017, 06:27 PM
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Welcome to the forum! It could also be the type of paper you're using; some are prone to retaining more of what you're sanding. If it gets little specks of wood stuck in between the grit on the paper then you have a lot of little hard, high spots that create that pattern. Make sure your paper is blown off and clean and check it as you sand to see if you're getting any of that before it cuts too many swirls. It also depends on the type of wood you're sanding. Some woods do this more than others.

Here's an example that's a bit on the extreme side but all it takes is one to make swirls -
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post #5 of 10 Old 10-19-2017, 08:04 PM
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Skipping grits during the sanding sequence will definitely cause the swirls to be noticeable. Corning as shown above will also cause the problem, although usually to a worse degree. I keep a small wire brush and a sand paper eraser block handy to clear the paper if it starts to clog. Cheap sandpaper that doesn't have uniform grit size can also cause the swirls. With a 1/4 sheet sander, the pad or platen, must be flat and you have to keep it flat on the work piece. I recently purchased a new Makita 1/4 sheet sander after my 43 year old B&D died and the platen was not flat across the entire surface. This caused swirls in all grits. Warranty replacement at the local tool store corrected the issue.

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post #6 of 10 Old 10-19-2017, 08:45 PM
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It's a combination of using too coarse a grit sandpaper and your sander. Some sander run faster than others and the slower the sander the more swirl marks show. You probably have more swirl marks with the 1/4 sheet sander. They are really considered a finish sander and made for very fine sanding or sanding between coats when finishing.

Like others have said you can't go from coarse paper to fine without either sanding a long time with the fine paper. It really needs the medium grit paper to eliminate the swirl marks. Another thing that helps is if you would take a damp cloth and wipe the wood with it and raise the grain when you make grit changes. This would make sanding more effective.
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post #7 of 10 Old 10-19-2017, 09:47 PM
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How hard are you bearing down on that sander? Looks like a corner dug in from uneven pressure. Like said even pressure, let the sander work and dont push it. Too much pressure can slow down the cutting because the sawdust cant get out from under the paper as easy. Dont ask how I know this.
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post #8 of 10 Old 10-20-2017, 09:59 AM Thread Starter
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Thanks for all the responses. I will definitely try to do the sand paper progression a bit closer. I will also try the mineral spirits whipping in order to see the swirls before I stain. I use a sandpaper cleaning eraser most of the time for most of the courser grits but not so much for the finer grits.

Thanks to all.
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post #9 of 10 Old 10-20-2017, 12:05 PM
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Are you using a electric Orbital, or an Air? I find this issue most common with electric ones. The Air sanders can spin at a higher rate which helps prevent this. Also, be sure not to start or stop your sander with it on the surface, and don't tip the sander. It also helps to do a quick once over, sanding with the grain after each grit. Peel off the disk you just used, fold it in half and sand with the grain over the major parts. Then do the next grit. Not only does it help take out fine swirls, it also helps you spot them. Depending on the starting surface, and the final finish you are going for, I usually only use 2 grits with an air orbital. 180 then 220 - done.

I prefer wiping the wood with Denatured Alcohol prior to stain to check for things like this. Evaporates off faster.
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post #10 of 10 Old 10-22-2017, 11:03 AM
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Unhappy dark mark after staining

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Originally Posted by Jassper View Post
Are you using a electric Orbital, or an Air? I find this issue most common with electric ones. The Air sanders can spin at a higher rate which helps prevent this. Also, be sure not to start or stop your sander with it on the surface, and don't tip the sander. It also helps to do a quick once over, sanding with the grain after each grit. Peel off the disk you just used, fold it in half and sand with the grain over the major parts. Then do the next grit. Not only does it help take out fine swirls, it also helps you spot them. Depending on the starting surface, and the final finish you are going for, I usually only use 2 grits with an air orbital. 180 then 220 - done.

I prefer wiping the wood with Denatured Alcohol prior to stain to check for things like this. Evaporates off faster.
Greetings fellow woodworkers, I am new to the site. I've installed solid oak hardwood floor, sanded it with an 4 head orbital sander slowly, from 36-60-80 to 100 grit. Floor is even, butt joints and all really good. When I stained I did have a few swirls that I missed, but halfway in the room, I had some small semicircular dark marks or discolorations would be a better description. Not scratches or swirls but a mark maybe left from the pad of the machine? I've done quite a bit of woodworking. You can't see this until you stain. My problem is when I spot resanded the small spot, when I restained, the spot looks duller from an angel. I've tried hand sanding slowly with the grain light pressure with higher grit 150 and hand orbital 150 grit light pressure. The stain looks ok, but the sheen of the spot is duller. It looks worst that the original mark. I have had fans on the floor all night to dry it. These are marks of some kind, not stain left on the surface. Any advice before I go further? I'm afraid to finish that these dull spots will show. Could it be oil out of the machine? I can get the black mark out, restain, matches, looks good, but from an angle the spot has a duller sheen.

Last edited by builderbob0729; 10-22-2017 at 12:33 PM.
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