Q: How can I remove water spots and food stains from a coffee table that has a marble top? Do you have any recommendations on how to protect a marble surface from staining? -- J.T.J.

A: As hard as marble is, it can show stains even from a glass that leaves only a moisture ring. These stains usually can be buffed out with polishing powder specifically designed for marble, such as tin oxide, which is available from hardware stores or from a marble dealer.

For marks caused by foods containing a bit of acid -- fruit juices, vinegar and wine, for example -- the polishing powder might not be effective in removing stains that have been etched into the surface. In such cases a poultice is required. This sounds difficult, but it isn't if a step-by-step process is followed.

A poultice can be made of white blotting paper, white paper napkins, white cleansing tissue, commercial whiting or a powdered household cleaner. The poultice should be soaked in the proper solution, which depends on the type of stain, and kept from drying while it is on the marble. The poultice can be covered with a piece of glass or a sheet of plastic, which will keep the moisture from evaporating while the stain is being drawn out of the marble. This process may take from one hour to 48 hours, depending on the stain.

Organic stains can be caused by such things as tea, coffee, wet bark, flowers and leached colors from paper or textiles. These usually take the shape of the staining object and will often disappear without treatment after the staining substance has been removed. To hasten removal of stains, wash the surface with clean water and apply a poultice soaked with hydrogen peroxide {20 volume} or household ammonia at full strength.

For oil stains caused by butter, milk, cream, salad oils, peanut butter, mustard or hand cream, use a poultice soaked in amyl acetate or acetone. Rust stains are orange or brown and follow the shape of the staining object. The stains are caused by steel wool, flower pots, some soils, nails, bolts, screws and cans. To remove the stain, use a poultice soaked in commercial iron rust remover.

After the stain has been removed, wet the surface with clear water and sprinkle on polishing powder. Rub the powder onto the marble with a damp cloth or use a buffing pad powered by an electric drill. Continue buffing until the etch marks disappear and the marble surface shines. If the etch marks persist, consult a marble dealer.

After the marble has been cleaned and buffed, use a nonyellowing wax for further protection. This light coat of wax is the only protection marble needs. These instructions are suitable for marble, but they may damage other materials. If you are not sure that the item you are cleaning is genuine marble, check with a marble dealer.

Q: My problem is the yellowing of joints between wall tile in an older bathroom. Apparently nonyellowing grout was not available when this house was built.

Because this condition exists on a vertical surface, it is impractical to apply a thick paste containing a bleaching agent because of the numerous joints to be covered.

Any suggestions you might have would be helpful in improving this ugly yellow staining between the all-white tiles. -- G.C.

A: A bleach-type poultice is the best method for removing the yellow stains. Though it may seem impractical to do this on a vertical surface, the method is recommended by the Marble Institute for plastering large areas of vertical marble surfaces and it should be just as feasible for ceramic walls.

First, wash the area with hot water and wipe dry. While the grout still is damp, apply a thick plaster made of abrasive cleaning powder with bleach and hot water. Apply up to a half-inch thick if possible and let stand for 24 to 48 hours. Remove the poultice with a wood paddle. The powder may be used again for general cleaning purposes.

Q: There is a product on the market called De-Solv-It, made by Orange Sol Inc. of Chandler, Ariz. The cleanser removes tar, grease, crayon marks, chewing gum, creosote and residue from bumper stickers, masking tape, store labels and contact paper. De-Solv-It, which can be used safely on plastics, contains petroleum distillate. -- J.N.

A: I recommend that when trying any solvent for removal of a residue, test the product in a small inconspicuous area to ensure that it does not damage the surface that you are trying to clean.

Send inquiries to Here's How, Copley News Service, P.O. Box 190, San Diego, Calif. 92112-0190. Only questions of general interest can be answered in the column.