Q: The flooring in our covered patio is referred to as terrazzo. It is dirty, and regular cleaning solutions do not seem to work. Does this type of flooring require special cleaners? If so, what kind of products should I use, and how should the floor be cleaned?

A: Terrazzo is a mixture of cement and small bits of marble and granite. Because the cement is porous, it tends to absorb stains.

A coating of penetrating sealer (such as Sparks Stone Glamour) will help prevent the absorption of stains. Some of the newer terrazzo floorings are made with synthetic resins such as urethane or epoxy in place of cement. These do not stain as readily.

For maintenance, a terrazzo floor should be vacuumed or swept regularly and damp-mopped with a mild cleaner such as Murphy's Oil Soap. It's best to avoid general all-purpose cleaners, detergents and wax removers. Never use petroleum-based cleaners, like Endust or Pledge, for dust-mopping terrazzo. The oil can penetrate the surface and cause permanent staining (Murphy's Oil Soap is all right to use because it is made from vegetable oil).

When cleaning, use a wet mop to apply the cleaning solution and let it soak on the flooring for several minutes. Rinse the mop with clear water, wring dry and then remove the dirty solution. Change the rinse water often.

If the staining and dirt resist general cleaning, it would be best to rent an electric scrubbing machine and use it with a stronger solution of neutral cleaner. Once your flooring has been cleaned and is thoroughly dry, apply the penetrating sealer. Sparks Internacional Finish is a top coating that can be added to ensure a scuff-, scratch- and mar-resistant surface.

For information on the availability of Sparks products in your area, contact Sparks Southwest Inc., 1804 Industrial Blvd., Colleyville, Tex. 76034.

With a penetrating sealer and top coating, the porous surface is protected, and you can use a general cleaning product such as Simple Green for day-to-day cleaning.

Write to Here's How, Copley News Service, P.O. Box 120190, San Diego, Calif. 92112-0190, or e-mail copleysd@copleynews.com. Only questions of general interest can be answered.