Q. We rented our condominium for a year, but are now preparing to return to it as our permanent home.

When we decorated it, I invested in rather expensive wallpaper. My problem is that the renters did not take good care of our condo and some of the wallpaper is now smudged with stains. I would like to clean these walls, but I am unsure how to go about it. Do you have any suggestions?

A. If the wallpaper is washable, such as vinyl or vinyl-coated paper, most stains can be removed easily by applying thick soapsuds with a soft sponge, then rinsing well with clear water. Products such as 409 also work well and don't require as much rinsing.

If the wallpaper is not washable, or if a soap-and-water treatment is not effective, try removing the stain by rubbing gently with a soft gum eraser, or a kneaded wallpaper cleaner, which is available through major wallpaper outlets.

Sometimes a dry piece of fine steel wool can do an effective cleaning job.

For greasy stains, make a thick paste by mixing an absorbent powder such as talc, cornmeal or cornstarch with a grease solvent such as carbon tetrachloride.

Cover the stain with the paste and leave it on until the paste is thoroughly dry. Then brush it off with a soft cloth. Repeat the treatment if necessary.

Stubborn non-greasy stains can be treated as follows: Use acetone for stains such as nail polish and ballpoint pen ink. Hair spray also is good for ink staining. Other effective solvents include amyl acetate, also known as banana oil, rubbing alcohol, naphtha and turpentine -- primarily used to remove paint and varnish stains.

All of these solvents should be used cautiously because they can damage the wallpaper finish or the printed dyes on the paper as well as the wallpaper paste. Test in an inconspicuous area. Use a cotton ball dampened in the solvent and sponge the stain lightly. Repeated applications of a small amount of solvent are better than a few applications of larger amounts.

Change the cotton ball used for sponging when it becomes soiled. Work from the center of stains toward the outer edges. Avoid hard rubbing that might roughen the surface.

Sponge the stain with the cotton ball at the edges to lessen the chance that the solvent will leave a ring.

Use care in working with solvents that are flammable. Be sure that the room is well ventilated. Use only small amounts and cap the container while you are working.

Never use flammable solvents near any type of open flame or heater. If solvent gets on your skin, wash immediately.

Q. I was given a very nice table that has an inlaid leather top. It is in fairly good condition, except that the leather is somewhat sticky and has several small indentations on the surface, which might have been caused by glasses. What is the proper way to clean and care for this leather top?

A. The sticky condition is usually the result of using polishes, such as wax on leather, which should not be done.

Leather needs oiling to retain its natural beauty. You can wash the surface with a mild soap, such as saddle soap, following the directions on the label.

Another recommended cleaning method is to clean the surface with a cloth dampened with mineral spirits; wipe dry. Repeat this process until all wax buildup is removed.

After the leather has been cleaned, apply lemon oil -- natural lemon oil, not a lemon oil furniture polish. Reapply the lemon oil several times in the following weeks.

The leather will absorb the oil, and all indentation marks will slowly disappear. Afterward, a little lemon oil every two or three weeks is all the care your leather-top table will need.

Q. The hearth of my stone fireplace is black slate, which is quite dull and dingy. How can I clean it and make it attractive?

A. Scrub the slate with a strong solution of detergent. Spread this over the surface and let stand for several minutes. Then, with a fresh solution, scrub the surface with a stiff brush.

After the slate has been thoroughly cleaned and allowed to dry, apply a solution of half turpentine and half boiled linseed oil, heated over boiling water.

Apply warm to the slate and let set for an hour. Wipe off the surplus. Apply two or three coats of this preparation. Let dry thoroughly between each coat. This is a rather tedious process but worth the effort.

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.