Better butter storage, and other tips from Martha

Q: I received a beautiful, handmade French butter keeper as a gift, but I'm not sure how it's used. Are you familiar with this type of dish?

A: Many people like to leave butter at room temperature because it's easier to spread. A French butter keeper — also called a bell or a crock — is a popular way to do this. It consists of a cup that is packed with butter and placed upside down in a water-filled base to form an airtight seal. Not only does a butter keeper make an attractive serving dish, it also keeps butter fresher longer than a regular butter dish. To maintain the seal, replenish the water every few days and keep the butter cup filled.

A butter keeper is not a foolproof substitute for refrigeration. If you live in a hot climate or if the crock is left in direct sunlight, butter won't stay fresh for long, and it will melt. Regardless of which container you use, I find that salted butter keeps better at room temperature than unsalted butter.

Q: Is it possible to change the color of my favorite leather sofa?

A: Leather sofas — like pumps, purses and pants — can be given new color, but you'll need to hire a professional for the job. The method she'll use will depend on the type of sofa you have, says Lonnie McDonald, an upholstery expert with the Institute of Inspection, Cleaning and Restoration Certification.

Pieces made from pigmented leather, which account for about 80 percent of all leather sofas sold, can be recoated with urethane paint. You can choose any color, but McDonald recommends selecting a similar shade, because a radically different base color will show through scratches on the new surface. Sofas made from aniline-dyed or nubuck leather must be spray-dyed. With this process, the leather can only be made a deeper shade of the same color, for example, switching from light brown to dark brown. Both treatments cost significantly less than reupholstering, but you may still spend up to $1,000, depending on the size and design of the sofa.

Q: What's your favorite material for kitchen countertops?

A: I really like honed marble. In fact, I have honed-marble countertops in three of my kitchens. The stone I like the most is from Vermont, a white statuary marble with subtle veins of gray and tan. Marble surfaces are excellent for rolling out dough, so even if you don't install it throughout the kitchen — the material can be expensive — you might consider it for an island counter or a small baking station. Marble is porous, so it must be sealed regularly to prevent staining. You also can choose to have it periodically polished, although I don't bother, because I like my counters to age over time.

Q: What are some options for making a bathroom window that faces my neighbor's property private?

A: My advice would be to replace the entire window unit with one that has frosted glass. This will let daylight filter into the bathroom while keeping the room private. A window dealer in your area should be able to fabricate and install the new unit for you. You might ask the dealer to incorporate a louver into the window to help ventilate the bathroom.

Keep in mind that if the window is positioned near a shower or bath, local building codes may require that it be made of shatterproof glass, also known as safety glazing. This glass is available only in clear form, but you can apply a tinted film to it. Alternatively, you can install waterproof window treatments, such as metal blinds or vinyl shades.

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