Early sandpapers were made of natural minerals like pumice, flint, garnet, and emery fixed to a paper backing with glue or varnish. Nowadays, most sanding abrasives are synthetic materials — aluminum oxide, silicon carbide, and high-tech ceramic — that stay sharp longer and can be produced in microscopic sizes. Deposited onto backings of paper, cloth, or plastic, they are held in place with tenacious plastic resins that can withstand the heat and speed of machine sanding.

With better technology has come a host of specialized abrasive products: sanding belts and discs engineered to withstand the rigors of rapid stock removal without clogging; sanding blocks that flex to follow irregular contours; plastic-film-backed "papers" so fine they can gently polish away defects without harming furniture's finish. Norm takes full advantage of these improved papers, using his orbital, random-orbit, and belt sanders to shorten the time he spends at the task. But he always finishes up by hand, with a sheet of sandpaper wrapped around a sanding block. "A power sander can still leave little swirl marks," he says. "Nothing beats a final hand sanding for making sure a surface is smooth."

Clog Stoppers
The amount of abrasive on a piece of sandpaper affects the way it performs. "Open coat" papers have more space between each abrasive particle and so don't clog as quickly with dust. (Coarse grits are typically open coat.) In grits finer than 150, where clogging is less of a problem, most sandpapers are "closed coat," covered completely with abrasive. Hardwoods and metals can be sanded with closed-coat papers; open coats are best for soft woods like pine.

In addition, some papers are treated with zinc stearate, a soapy substance that prevents clogging. Don't use these so-called "nonloading" papers with water-based finishes, however; stearates can prevent the finish from adhering properly.

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