The word “burnish” is often used incorrectly when describing sanding with very fine-grit sandpaper. “Burnish” means to press with a hard, smooth object like metal or stone to compact, or compress, or polish a material. For example, to sharpen a soft-metal card scraper, you burnish the flat side using a hard-metal “burnishing” tool before rolling the edge with the same tool.
Compression is not what’s happening when you rub wood with sandpaper, no matter how fine the grit. Sandpaper cuts and makes sanding dust; it doesn’t compress. Very fine-grit sandpaper cuts finer and leaves a more polished-looking surface, but this is still not burnishing.
As for closing the pores, you can’t do this with sandpaper. You are always cutting, no matter how fine the grit you use. And cutting with a finer grit doesn’t impede the penetration of a liquid finish (though a stain may color less because the shallower scratches retain less pigment).
