In 1969, John Wayne won an Oscar for best actor for his performance in a movie called ?True Grit." "Grit" has a lot to do with performance when it comes to sandpaper. Those numbers printed on the back of a sheet of sandpaper tell you how big the abrasive particles on the other side are. With the same number of passes when you're sanding (using the same amount of pressure), the paper with larger particles sands deeper and rougher than paper with smaller ones. The lower the number, the bigger the grit. A low number tells you it's meant for rough sanding where a higher number has smaller grit, which means it's for smoothing and finish-sanding. Usually 30- to 60-grit papers handle the tough stuff, 100- to 150-grit handles medium jobs and 220-grit is used for finish-sanding. And that's the On The House tip for today.