Although one of the advantages of putting up prefinished wood paneling on interior walls is that it is virtually maintenance-free, most homeowners who have had wood paneling for a number of years eventually discover that this is not entirely true.

It is true that good quality factory-finished paneling will last for many years with only an occasional need for dusting or other cleaning, and that the need for periodic painting is virtually eliminated, but after a time finish does tend to get dull and cloudy looking and more than just a casual cleaning is needed to restore the original luster. There may also be scratches, nicks and other blemishes that mar the surface and detract from the original beauty of the finish.

Ine some cases the finish may be so severely worn and blemished that the only proper cure is complete refinishing of the wood by first stripping it down completely with a power sander or a chemical paint and varnish remover.

However, in most cases the homeowner can restore much of the original color and luster of the finish by a thorough cleaning and polishing, and by use of various touch-up materials to camouflage or cover minor blemishes. Needless to say, the job will be easiest on those panels where a good quality finish was applied originally regardless of whether they were factory finished or finished by the installer at home.)

Although a film of dirt and airborne soil is soon noticed on walls that are painted a light color, the same build-up of dirt and/or soil often goes unnoticed for years on dark-colored wood paneling where the change in tone and shading may be so gradual that it is not until the finish is quite dull that the homeowner finally realizes that the paneling looks much darker and less attractive than it did when originally installed.

Because of this, the first step is rejuvenating any wood paneling is to give the surface a thorough cleaning. Start vacuuming with a soft brush to remove all surface dust. Then experiment on one small area with various other methods of cleaning.

Washing with detergent and water is seldom advisable or even safe for the wood or its finish because water can ruin many finishes. It can also raise the grain of the wood so that a rough, dull-looking area is left. Instead, try wiping with a cloth saturated with one of the various cleaner-polishes sold for use on furniture and paneling. Be sure you start with a clean rag, turning it frequently as it picks up dirt. Discard this cloth and start with a fresh one when and if the entire rag gets dirty. The biggest mistake people make is rubbing polish on with a rag that becomes saturated with dirt -- this only spreads the dirt around.

If this doesn't do the job of removing surface soil and grime, a more drastic cleaning may be required, using a ray that has been saturated with a solvent such as a paint thinner, or one of the liquid grease solvents now sold in place of carbon tetrachloride (these are non-flammable). As a rule, paint thinner will work better on many finishes, but it is highly flammable so must be used with care. Both should be used only in a well ventilated room and, when trying either one or both of these solvents, experiment on a small, inconspicuous area first to see if it has any effect on the finish.

If a test indicates that the solvent cleans and brightens the surface (it may dull it slightly, but this is only because it is removing some of the old wax or polish), you can go ahead with cleaning the entire wall. Here again, wipe with a cloth, turning it to a clean surface as soon as it gets dirty. For best results work one small section at a time, then immediately wipe that area with a dry rag before going on to the next section. The idea is to remove the solvent -- and the dirt it has loosened -- before it dries back onto the surface again.

If your first test with the solvent seems to indicate that this damages or removes the finish, the only other cleaning method to try is a mild nonsudsing detergent. Wipe this on with a clean sponge, allow to set for two or three minutes, then wipe off with another sponge that has been dampened with water. Frequent rinsing of both sponges is advisable.

When the surface has been cleaned, the next step is restoring the luster by waxing or polishing. As a rule, one of two methods can be used: The first method is to use paste wax, rubbing on vigorously in thin layers, and changing the cloth as soon as it shows signs of soil (it will pick off dirty wax and old polish if any is left on the surface). The wax is then buffed can be used to speed the job, but most disk-type buffers tend to leave visible swirl marks.

The method is to use an oil-type polish instead of wax. This is generally a little easier to apply (you don't have to rub as hard as with paste wax), and gives a more satiny, oiled type of finish, but it may have to be renewed more often than a hard wax would. If an oil-type polish is used, remember that it should not be applied over wax -- this will result in a dull smeary finish which will be almost impossible to buff to a shine, and which will have a tendency to attract dirt. If all old wax has been cleaned off (or if wax was never used on the panels), an oil-based polish will maintain most finishes in excellent condition with a minimum of maintenance.

Small scratches of nicks can be touched up to make them less noticeable by using an artist's watercolor brush (these come to a point) and a suitably colored stain. Most paint stores have a variety of shades, as well as small bottles of touch-up stains, but you won't always be able to find the exact shade or color you want. You may need more than one color -- one tone for some of the lighter colored areas of your paneling, and a darker tone for scratches in the darker areas. To match each there are two methods you can use: One is to buy several cans of stain and mix them in diferent proportions until you arrive at the needed shade; the other is to buy a small can of clear wood sealer and mix your own stain by adding small quantities of tinting oil colors to this.

Whatever method is used, remember that satin colors in the can, or on a color card, are only an approximate indication of the actual color they will be when applied to the wood -- all woods take stain differently. The only way to know for sure is to test and experiment on the actual wood, either on a scrap piece of in an inconspicuous surface.