Dear Martha: Can I clean the string on my strand of pearls?

A: Washing pearls with a mild soap solution is generally considered to be a safe cleaning method, but the best way to take care of a discolored thread is to have the necklace restrung by a reliable jeweler. This inexpensive process should be done yearly regardless of the string's cleanliness, as the nylon or silk holding the pearls together deteriorates over time and may break with regular wear.

To prevent the necklace from getting dirty, make it the last item you put on while dressing and the first one you take off. This minimizes the contact the piece has with body lotion and cosmetics that may stain the string and cause pearls to lose their luster. Before storing, wipe the strand of pearls with a damp, soft cloth to remove residual body oils. Then slip it into a fabric pouch. Because pearls can be scratched by other jewelry, they should be stored separately.

Dear Martha: Can I add shredded financial documents to my compost heap?

A: The key to successful composting is maintaining a balanced mix of nitrogen and carbon. This ensures that sundry additions can be effectively transformed into the nutrient-rich soil conditioner prized by gardeners. Nitrogen sources (also called green, or wet, matter) include vegetable scraps, grass clippings and eggshells. Materials that provide carbon, such as fallen leaves, wood chips and old potting soil, are considered brown, or dry, and should make up the other half of the heap.

Paper is a suitable source of carbon. Because computer printouts, credit card statements and other processed paper decompose slowly, shredding them - or tearing them into small pieces - will guarantee that they break down more quickly. To prevent the paper from forming an impenetrable layer in the compost heap, mix in a few handfuls at a time, alternating them with other green and brown materials.

In general, though, these documents should be composted in limited quantities. Conventional recycling is a more efficient way of giving paper a second life than composting, says Jean Bonhotal, a compost specialist and the associate director at the Cornell Waste Management Institute. A few shredded bills should not be a problem. But avoid large amounts of heavily bleached sheets, which may introduce unwanted chemicals to the heap, Bonhotal says.

Other types of paper more appropriate for composting include soiled paper towels and coffee filters (preferably unbleached), shredded brown bags and newspaper torn into strips (colored pages are acceptable, Bonhotal says, as the ink is usually soy based). But do not add glossy magazine pages and newspaper inserts, as they may contribute toxins and will be slow to decompose.

Dear Martha: What kind of baking sheet do you suggest using for

cookies?

A: Baking sheets generally come in two finishes: shiny and matte. Those with shiny, silver-colored surfaces work best: The finish deflects some of the oven's heat rather than absorbing it, resulting in cookies that bake evenly and are less likely to burn on the bottom. For this reason, avoid nonstick baking sheets, which tend to have a dark matte finish and thus absorb more heat.

As a rule, line sheets with parchment or a nonstick baking mat; the latter is especially important when making cookies, such as tuiles, that require a nonstick surface. Aluminum, which conducts heat well, is a good material to look for. Purchase a sturdy sheet; flimsy ones are prone to warping and then won't heat uniformly. Insulated, or double-layer, sheets contain a built-in air cushion that is designed to prevent overbrowning.

The size of a baking sheet is another factor. It should fit in your oven with at least two inches to spare on all sides, so that air can circulate. Also consider the size of your refrigerator and freezer, since some recipes call for chilling rolled-out dough or preshaped cookies. Whether to opt for rims is a matter of preference. Rimless ones allow cookies baked on parchment to slide off easily; rimmed versions provide a better grip.

Questions should be addressed to Ask Martha, care of Letters Department, Martha Stewart Living, 11 W. 42nd St., New York, NY 10036. Questions also may be sent by e-mail to: mslletters@martha stewart.com. Please include your name, address and daytime telephone number.