On this day in 1965, "Days of our Lives" premiered on television. "Like sand through an hourglass, so are the days of our lives." Today, we'll talk about sand, the kind that is stuck on paper. Sandpaper, technically known as "coated abrasives," has confusing but important numbers printed on its back. They provide a wealth of information -- if you can break the code. Grit is most important. If it says 80 it means the abrasive particles passed through a screen with 80 openings per inch. Abrasive type is next. Garnet is the old, economical standby, but aluminum oxide and silicone carbide are two popular synthetics that are much tougher. Paper-backing weight is indicated by a letter (usually A B or C) for hand- or light-power sanding. "Open" or "closed" coat tells how much of the surface is covered with particles. Open has less and will not load up as quickly as a closed coat. And that's the On The House tip for today.