You’re finally done sanding, everything looks beautiful, and then you apply your stain, and end up with a disaster like this:
This was one of my first refinishing projects, and as you can probably guess, I learned a lot about what not to do that day.
Hopefully your sander marks aren’t anywhere near as bad and ugly as mine were, but I’ve got you covered either way!
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How to Avoid Sander Marks
So, lets get something straight: sander marks are unavoidable. They’ll always be there, because that’s how sandpaper removes the wood.
Even if you hand sand, whenever you run sandpaper against wood, sanding marks are created.
But it’s actually pretty easy to minimize their appearance, and make them small enough that they’re invisible to a viewer.
Step 1: Sand Normally
Start with whatever sandpaper grit you plan to use (which depends on your project and what you’re trying to accomplish – if you’re not sure, check out this guide to sanding here.)
I usually start with 40 grit if I’m trying to remove paint, a finish, or a really gnarly manufacturing job, but if it’s just normal wood in decent condition, then I’ll start with 80 grit.
Run your sander with the grain, so that any sander marks are in the direction of the grain. This is particularly important if you’re using a palm sander or belt sander, since they create linear marks. Later on, the grain will hide any small remaining marks.
Orbital sanders create swirly marks, so this a bit less of concern, but sanding with the grain is still a good habit to have.
As a warning
Wood and finishes are removed faster if you sand perpendicular to the grain. Don’t do it. If you’re feeling really impatient, then sanding at a 45 degree angle to the grain is the most you should try.
As a fun fact, the marks in the picture above were created with a belt sander and 36 grit sandpaper, and they’re particularly terrible because I got impatient and sanded against the grain. Don’t be like me. Sand with the grain.
Don’t push your weight onto the sander. I know it seems like that’ll make the sander sand faster, but it actually doesn’t. Instead it stresses the tool, slowing it down and creating deeper sanding marks.
One more thought
If you have a variable speed sander, don’t worry about choosing a lower speed. That doesn’t actually reduce sander marks, it just affects how fast the sander sands.
Variable speed sanders are really useful if you’re sanding plywood or something else where you only want to remove a little bit of wood. But in most cases, using the highest speed is your best bet.
Step 2: Sand With Higher Grits
So if you start with a low-grit sandpaper, you have some pretty deep marks in your wood. The best way to get rid of these marks is to sand with the next grit up.
If I started with 40 grit sandpaper, then I’d want to sand again with 60 grit sandpaper. Then 80. Then 120.
And so on, until you hit 180 grit sandpaper.
Be sure to vacuum or wipe off your piece between grits. Otherwise, larger sawdust from the lower grits might get trapped between your sandpaper and the wood, creating the exact marks you’re trying to remove.
I usually stop sanding at 180 grit, because if you sand too much you risk clogging the pores of the wood with fine sawdust, which makes it harder for the wood to absorb stain.
That said, sometimes 180 grit isn’t enough to hide all of the sanding marks, so I usually perform a check before staining/finishing.
Step 3: Check Your Work
Usually 180 grit sandpaper is enough, but occasionally it isn’t, so it’s really worth double-checking to make sure all the marks are invisible before moving on.
If you haven’t realized, on most bare wood, sanding marks are almost invisible to see. But as soon as you apply stain or finish, they’re bright and obvious.
But luckily, there’s an easy way to highlight them beforehand.
Simply grab some mineral spirits, and wipe them onto the wood. Water works too, but it raises the grain of the wood, so you’ll need to sand it back down afterward if that’s what you choose to use.
When wood gets wet, sander marks stand out, making them nice and obvious for you to see.
If necessary, sand with a higher grit sandpaper to remove those sander marks, and try again.
(Optional) Step 4: Hand-Sand One Last Time
Hand sanding creates lighter, linear marks, so if you’re a perfectionist, you could sand to 220 grit sandpaper with the power tool, then return to 180 grit sandpaper and sand by hand.
That last hand sand will remove any scratches from the machine, and leave you with a truly flawless piece.
I’ve…never done this. Honestly, I just don’t have the patience for hand sanding, and I’ve always been happy with the result at 180 or 220 grit paper with the orbital sander.
Removing Deep Sander Marks
Okay. So maybe you’re did all this and still had sander marks. The above table I showed you? I did this whole process, and still got marks.
Why? Because I sanded against the grain with a really aggressive sander and a low grit. My attempts to remove those marks with an orbital sander were akin to trying to remove sharpie from a wall using a dry tissue.
So if you’re in a situation like mine, there are a couple things you can take away:
- You should be trying to remove marks with the same level of sander that made them. If you used a belt sander, remove belt sander marks with another belt sander.
- If you sanded across the grain, the best bet for removing those marks is with a lower grit sandpaper than you started with, sanding with the grain.
If that’s still not working, grab a more aggressive sander (obviously making sure to sand with the grain this time, and working your way up WITH THAT SANDER.)
Sanding perpendicular to the grain creates marks that are near impossible to remove, so you know, try not to do that.
Other Sanding Swirl Tips and Tricks (and Myths!)
Use the Vacuum Attachment
As I mentioned above, if larger sawdust gets trapped between the sandpaper and the wood, it can create sanding marks just like the sandpaper does.
And those marks can be difficult to remove, because you’re now sanding with a grit that’s finer than the size of that sawdust.
Most sanders have a vacuum port on the back. Actually attaching a shop vac to your vacuum port can go a long way for removing sawdust from your piece, and therefore reducing sanding marks.
Please ignore my makeshift vacuum hose adapter (aka, a bunch of tape.) Clearly, I was desperate.
If you’re following the procedure listed above, sandpaper quality won’t effect whether you get swirl marks or not. I’ve tried both cheap and expensive sandpaper, and there’s one big difference I’ve noticed:
Cheap sandpaper tears more easily.
I used to buy Harbor Freight sandpaper sheets and run through them like candy because they lasted like 5 seconds. Then I bought 3M sheets, and they lasted forever.
Sand never fell off either paper and I got sander marks with both, because as discussed above, swirl marks are pretty much unavoidable.
These days, I have a Dewalt Orbital Sander (which I love!) with a hook and loop (aka, velcro) pad.
I buy the sandpaper on Amazon, usually from whichever random brand has the grits I need. This sounds sketchy, but it’s actually great.
For around $10, you usually get 60-100 sandpaper sheets, which is more than the 10 sheets you’d get at Home Depot for that price.
And I’ve found they still last quite a long time. Given the price difference, even if they only lasted two sandings, I still think they’d be a better deal.
I briefly mentioned this above, but I wanted to reiterate it in a bit more detail: don’t put extra weight on the sander when you’re sanding.
You want to hold the sander firmly, yes. But you shouldn’t be pressing directly down onto the piece when you sand.
This slows down the sander, stresses the tool, and creates sander marks in the wood because of the extra pressure.
Along these same lines, you shouldn’t be tipping the sander, or putting more weight on one side than the other.
Not only will this sand your piece unevenly, but it will create deeper marks on that side, and wear out the pad on your sander faster.