It heats! It cools! It rotates 2 ways!

Q: I've been told that ceiling fans should turn different directions in the winter and summer. Why is this, and which way goes with which season?

A: A ceiling fan is a wise investment, as it will pay for itself over time with reduced home-energy bills. In summer, a fan provides a light breeze to make you feel cooler. In winter months, it recirculates warm air so you can turn down the thermostat. To get the maximum energy-saving effect, adjust the rotation direction of your ceiling fan to fit the season.

When the weather is warm, run it on the normal, or "forward" setting (counterclockwise), which propels air downward and creates a refreshing breeze that can make a room's temperature seem up to eight degrees cooler.

During the winter, reverse the fan's direction so the blades rotate clockwise, and operate it at a slow speed. Because hot air rises, the upward draft created by the fan pushes the warm air — which is hovering near the ceiling — throughout the room.

Q: How can I keep decorative cookie and candy tins from rusting?

A: Years ago, everything from tea and tobacco to crackers and candies came packaged in metal boxes, usually made from tin. The exteriors of these tins were decorated with company logos, artwork and graphics — designs that make them especially appealing to collectors.

Even now, some manufacturers sell their products in tins that might someday evoke the same nostalgia (although modern versions are usually tin in name only).

Unless the metal constituting a decorative tin is galvanized, it easily can play host to blooms of rust, which can spread and corrode your collectible before you know it. John Singer, a chemist in New London, N.H., says the best way to stave off rust is to apply a coat of clear lacquer inside and outside the tin.

It's important to do a test before applying the lacquer, as there's a risk that it can act as a solvent to the ink in the designs. Certain types of ink that were (and are sometimes still) used on tins are particularly vulnerable to this.

Find an unobtrusive spot on the tin, and dab a tiny bit of the lacquer there to see whether the ink dissolves. If it does, or if there are no spots you feel comfortable testing, apply a thin coat of carnauba wax — often used for floor or car waxing — over all exposed surfaces. This will block moisture and discourage rust, but may require periodic reapplications.

If you plan to use treated tins to hold cookies or other food, line them with parchment paper or aluminum foil so the food does not come in contact with the coated tin. And if a tin gets wet, dry it right away and then reapply lacquer or wax if needed.

Questions may be sent to mslletters@marthastewart.com or Ask Martha, care of Letters Department, Martha Stewart Living, 11 W. 42nd Street, New York, N.Y. 10036. Sorry, no personal replies.