Dear Martha: Is it really necessary to poke a potato with a fork before baking it?

A: You have to spend only one afternoon cleaning bits of potato inside your oven to know that exploding tubers aren't an old wives' tale.

Because of their tough skin and moisture content, these root vegetables build pressure inside as they're baked.

Small holes in the skin are necessary to release that steam - just a few on both sides of the potato will do the trick.

For best results, place potatoes directly on an oven rack so that air can circulate around them.

Wrapping spuds in aluminum foil is not recommended, as trapped steam results in less crisp skins.

When baking sweet potatoes, remember to put a cookie sheet on the rack below them to catch their juices - it's no fun cleaning up that, either.

Dear Martha: What causes sweaters to pill?

A: Pills, the unsightly, fuzzy balls that form on sweaters and other clothing, occur when a garment's fibers come loose and rub together or against another material.

Certain high-friction areas are especially prone to pilling: under the arms, for example, or on the shoulder from which a purse hangs.

Buying well-made sweaters makes a big difference. Lower-quality products contain a high percentage of short fibers, which are quick to loosen.

While wool is susceptible to pilling, other natural fibers, such as cotton and silk, are not.

Synthetic fibers, such as nylon and polyester, conduct static electricity, which attracts lint and thus accelerates pilling. Pills produced by these kinds of fibers are also particularly tough to remove.

To determine if a sweater will pill excessively, rub the fabric gently between two fingers. If pills start to form on contact, keep shopping.

Also, examine the sweater closely to make sure its knit is tightly woven, and check the ply of the yarn.

Many sweaters come with a packet of spare yarn for repairs, which allows you to inspect a strand to ensure that it's at least double-ply.

Be wary of sweaters that are covered in a layer of fuzz: This is a trick that manufacturers use to make lower-quality fabric feel softer. It may seem luxurious at first but will almost certainly lead to pilling.

Once you buy a sweater, proper care will minimize pilling. Hand-wash garments, and lay them flat to dry. If any pills do form, remove them at the first sign.

The simplest method is to skim them off gently with a fine-toothed hair comb.

Specially designed fabric combs and battery-operated sweater shavers are also available - just be certain to inspect your garment for snags and tiny holes, problems these devices can worsen. *

Questions should be addressed to Ask Martha, care of Letters Department, Martha Stewart Living, 11 W. 42nd St., New York, NY 10036. Questions may also be sent by electronic mail to: mslletters@marthastewart.com.