Q When buying a new mattress, why is it so urgent that the box spring be replaced? I can't see why it's necessary. What are some suggestions when looking for a new mattress?

A A new box isn't necessary if the old one doesn't have rips, warps, creaks, or "give," according to Consumer Reports Magazine.

On the other hand, the Better Sleep Council, a nonprofit organization supported by the mattress industry, warns that pairing a new mattress with a foundation it wasn't designed to work with will impede comfort and reduce the useful life of your new mattress.

On the sales room floor you may be told that the mattress and box spring are designed to work together. Indeed, the material cover on the new mattress and older box spring won't match, and, depending on the mattress you are buying, it might be inadequately supported by the old box spring. You might also hear that you must include a box spring to protect the mattress warranty. But be sure you read just what the warranty covers.

Educate yourself before mattress shopping:

• Decide on type: innerspring, foam, air, adjustable or water bed.

• Test your choice. There's no one "best" mattress. People have different notions of comfort. Go to a showroom and look them over. Plan to spend some time testing them: five minutes lying on your back, five on each side, and five minutes on your front if you're a belly sleeper. Do this with your bed partner, if you have one. Don't be embarrassed; this is important and expected by sales staff.

• Ask about a return policy. Some dealers let you test them at home for 30 to 90 days.

• Watch for sales and don't be afraid to bargain. Realize, however, that it can be very difficult to comparison shop from store to store. The same mattress from a manufacturer can have different names depending on who's selling it. You'll need to learn what makes up the mattress of your choice, how many layers, made of what and the thickness of each, for example.

• Avoid buying online unless you've experienced the mattress you are buying.

• Ask if they will take the old mattress when they deliver the new one.

More information and other tips: www.bettersleep.org and www.consumerreports.org. Type "mattress" into the search window.

More on salvaging books and documents

In addition to the Minnesota Historical Society, the Midwest Art Conservation Center is a nonprofit regional center for preservation and conservation of art and artifacts providing treatment, education and training for museums, historical societies, libraries and other cultural institutions. They also advise and care for objects from the general public. Preservation Services provides 24-hour emergency disaster response to member and nonmember regional institutions. For more information go to: www.preserveart.org, or call 612-870-3120.

Patricia Ewer, conservator, Mound

Send your questions to Fixit in care of the Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488, or call 612-673-7032, or e-mail fixit@startribune.com. Past columns are available at www.startribune.com/fixit. Sorry, Fixit cannot supply individual replies.