Run your sander with the grain, so that any sander marks are in the direction of the grain. If you used a belt sander, remove belt sander marks with another belt sander. Sand never fell off either paper and I got sander marks with both, because as discussed above, swirl marks are pretty much unavoidable.
Do you go through all the grits? What kind of sander are you using? Random orbit sander? Linear sander? Belt sander? I think you’ll find that the ROS typically is the ideal sander to use for large surfaces like a table top due to the type of scratch pattern it produces: random! The 80 takes the longest but once all the drum sander marks are gone, the other grits go a lot faster. Taking the sanding beyond 180 grit is a personal preference…heck, you could stop at 150 grit, too. If your sander has a dust port, be sure to hook up a vacuum to it. I use Festool sanders and they capture what seems to be about 99% of the dust from sanding. It really feels like you are doing nothing because you have no dust left from sanding but one swipe of your hand on the surface tells you otherwise.
how to get rid of belt sander marks Related Question:
How do you remove belt sander marks?
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.
Why does my belt sander leave marks?
If the inside of your sander has a lot of dust, there is likely an issue with the machine and it often shows in the materials run through the machine. Excessive dust buildup can result in burn marks or lines on the workpiece. Dust buildup can also cause tracking issues and prematurely wear out the belt.