A holiday such as Thanksgiving or Christmas offers a great excuse to haul out Grandma’s finest tableware and linens.

If they haven’t been used in a long time, though, they might be looking a little bedraggled. Here’s how to spiff them up so you can show them off.

China and crystal

Delicate heirlooms should be hand-washed in warm water with mild dishwashing soap, Jane S. and Richard W. Long recommend in their book “Caring for Your Family Treasures.” To guard against accidental damage, they suggest placing a rubber or foam pad in the bottom of the sink before you start, washing the items individually and using great care.

Rinse completely, and dry with a soft towel.

Never wash unglazed ceramics, because they will absorb moisture that could stain them or cause them to soften and break, they said. Don’t wash valuable ceramics or pieces with gold trim in a dishwasher.

Silver

Even carefully stored silver items will tarnish because of sulfur in the air. If the tarnish is just a light brown film, the Longs said it can be removed by gently washing in warm water with a mild detergent. Don’t immerse hollow-handled pieces or objects with indentations that might hold water, they caution.

They recommend drying the items thoroughly with a soft cloth immediately after washing, and using a dry corner of the cloth to put the silver pieces in their container without touching them. It’s also a good idea to wear clean cotton gloves when you’re setting the table or to wipe off the fingerprints.

If polishing is necessary, avoid abrasive commercial cleaners or homespun remedies involving baking soda and foil, which can be too harsh.

Jeffrey Herman, founder of the Society of American Silversmiths, suggests a mild cleaner such as Tarni-Shield or Twinkle, applied with a moist cellulose sponge.

The Longs, however, recommend using precipitated calcium carbonate, which is available from conservation suppliers. Mix a small amount with a 2 percent solution of mild detergent and water in a shallow dish to create a consistency like cream. Apply a small amount with a piece of clean flannel or a wad of loose cotton, rubbing gently in a circular motion. Replace the cotton or flannel often as you work.

After polishing, wash with mild soap and water and dry well with a lint-free cloth.

Linens

Fragile or valuable linens deserve extra care in cleaning them. If they’re so delicate or old that they can’t be washed, try vacuuming them by covering them with a protective nylon or plastic screen and using the low setting, with open vents, on your vacuum cleaner, recommends Cheryl Mendelson, author of “Home Comforts: The Art & Science of Keeping House.”

For items that can be washed, merely soaking in plain, soft, lukewarm water may be all that’s needed, Mendelson said. If the item is fragile, lay it on a nylon screen or in a plastic colander to immerse it in the water. After soaking, rinse in another bath of cool water.

If more cleaning is needed, she recommends adding some very mild, neutral detergent, such as Orvus WA Paste, to the water. Soak the item a few minutes, then pat the piece gently to get water to pass through it, or gently raise and lower the screen or colander. Rinse with cool water in the same manner until all the residue is gone.

Sturdier or less valuable items can be bleached in the sun or, if necessary, washed in a stronger detergent to try to remove spots and stains, Mendelson said. Avoid detergents with optical brighteners or bluing. Bleaching with a nonchlorine bleach or hydrogen peroxide should be reserved for items that aren’t particularly important or valuable.