The coarsest sandpaper usually available is 40 to 60 grit. You would use this type of sandpaper on your table if you need to strip the table or rough the table for stripping.
The medium-grit sandpaper is 80 to 120 grit. If you just need to remove a small imperfection, such as a ding, or if you need a paper for smoothing the surface of the table, then this medium-grit size is ideal.
Fine grit sandpaper is numbered 150 to 180 grit. If you want to finish your wood, and it is already fairly smooth, then you can use this grit of sandpaper for a final sanding before finishing.
Very fine sandpaper is in the 220- to 240-grit category. You would use this sandpaper if you needed to sand between separate coats of stains or sealers without removing the whole coat or roughing up the wood on the table. If you want to sand between finishing coats, however, you will need to use the next category of grit, which is the extra fine sandpaper.
The 280- to 320-grit sandpaper is known as extra fine. Like the 220 to 240 grit, it is ideal for sanding between different table coats. This sandpaper will work best for sanding between final coats and finishing coats. It can also be used to remove dust marks or dust spots.
The finest sandpaper available is 360 to 600 grit. It should be used to remove very small scratches on the table. You can also use this sandpaper to diminish the luster of the paint or stain on the table as well, without scratching or damaging the table.
Always purchase industrial-grade sandpaper from an industrial supply store, rather than commercial-grade sandpaper at the local hardwood store. The industrial-grade sandpaper is made from high-quality materials, which will enhance the sanding and aid in the quality of your project.