Sandpaper is sandpaper, right? Not exactly. Each piece of sandpaper has finely (or not so
finely) ground particles of rock attached to it. The type of rock and the
substrate attaching it to the paper – and sometimes even the paper – can vary
greatly between products.
“Running through grits” not only means going from coarse to fine, but also matching the abrasive to the job. Before you stockpile any more sandpaper, make sure what you do buy (and apply) is the right stuff.