Five Ways to Reduce Edger Swirl
The worst part about running the edger is the circular scratch marks it leaves behind. Sometimes these scratch marks are difficult to see (especially for a first-time floor refinisher)... until you apply finish, when they stand out like a sore thumb.
If you don’t realize that you have the dreaded edger swirl until after it’s been coated with a layer of finish, it will take an enormous amount of work to make it go away because you have to sand off all the finish first. But there are ways to reduce the visibility of those scratch marks.
Edger swirl is like sunburn; a small amount of prevention helps you avoid a large amount of pain.
Here are our five favorite steps to avoid it in the first place:
1. Don’t skip grits. Ever.
There are plenty of professionals out there who insist that it only takes three sanding grit passes to sand a floor, regardless of how damaged and scarred the wood is, but that is just plain foolish, especially if you’re worried about edger swirl.
If your floor condition necessitated a 16 grit start, you can’t jump to a 36 grit and then to an 80 grit, especially on the edger because you will still be able to see scratch from the coarse cuts.
The grit spectrum available for floor refinishing looks like this:
12grit 16grit 24grit 36grit(or 40) 60grit(or 50) 80grit(or 100)
Regardless of where you start in this spectrum, you must use all the grits that are FINER than your starting point. This way, the edger swirl is gradually but irrevocably eroded away.
The coarser the grit you use, the more difficult it is to remove the scratches it causes. These grit sequences have evolved over decades of trial and error. We know that each grit in this sequence is only capable of sanding out the scratch from the grit that came right before it.
People tell us that they skip grits all the time when they sand furniture. But when you sand furniture you start at 80 grit and move up from there. Your margin of error is much greater when you’re talking about those fancy fine grits; if you’re careful you can indeed remove 80 grit scratch with 200grit paper.
But the ability to skip grits breaks down when you’re working with the huge granules found on floor sanding paper. And grit scratch that is not removed shows up as edger swirl. So don’t skip grits, and don’t stop before 80 grit.
2. Use a nylon cushioning pad between your edger and the paper.
It softens and limits the down-grinding power of your edger, which limits the depth of scratch it can leave. These nylon pads do compress down as you use them, so replace them when they get too thin. And always get a fresh pad when you begin you final edger pass (either 80grit or 100grit) so that it leaves as little evidence of its own swirl as possible, while still taking out the 60grit scratch that came before it.
3. Use the B-2 edger.
Choose a 2-speed edger and use the lower speed for your 80grit (or100grit) pass. The slower speed makes the edger less aggressive, which reduces the visibility of the scratch, but still allows removal of the 60grit scratch that preceded it.
4. Don’t overuse your paper.
Sandpaper dulls more quickly than you think and dull paper does not remove scratch effectively. Our edger paper will be dull enough to comprise its scratch-removing ability after 20 linear feet of edging (assuming that you are edging about 9” off your wall). A good rule of thumb is to change your edger paper after two walls’ worth of sanding.
Don’t argue with me about how the paper still feels sharp or is still producing dust; these are not reliable indicators of sharpness. The only way you know if paper is still sharp is how cleanly it erases the visible scratch from the previous edger pass.
This is why edgers have headlights – to help you actually see the scratch you’re trying to erase. But if you can’t trust yourself to discern that, use light pencil lines all along your edger zone; if the pencil lines erase cleanly and easily as you edge, you are still working with sharp paper.
The moment you have to double back to remove a light pencil line, you have proof that your paper is too dull to erase edger swirl.
5. Use a flashlight to identify any remaining edger swirl and sand it out by hand before you even think about applying finish.
Even if you follow the first four directions, you are likely to still have some edger swirl. But by this point it should be shallow and easily erased with aggressive hand sanding parallel to the grain. When we’re in the field, we get on our hands and knees and use a folded over 80grit piece of edger paper to sand over every part of the floor touched by the edger.
Yes, you will be tempted to use a palm sander instead, but resist the temptation. Palm sanders can over-polish the floor, or at the very least leave a different texture where they were used, which will limit the absorption of your finish in those areas.
So, if you insist on using an orbital sander to remove swirl, you should still hand-sand over the area where you used the orbital. It is almost impossible to over-polish the floor with hand-sanding so your floor will absorb finish much more uniformly.