Interior woodwork is usually protected with some kind of clear finish. To clean any wood effectively without ruining this topcoat, you need to know what it was finished with in the first place. Here's a quick primer on finishes and how to clean them:

* Natural "drying" oils like linseed and tung oil soak into the wood surface, then dry hard to form a protective film that is all but invisible. Manufacturers recommend lemon oil polish, which partially dissolves the old topcoat. As you wipe it on, you also wipe away surface grime that has become embedded in the finish.

* Wax imparts a surface coating that can be felt and seen. It doesn't dry as hard as oils and builds up in the wood pores after repeated applications. To clean waxed wood, you can use a commercial wax stripper, a mild solution of white vinegar and water, or lemon oil polish, but you'll have to reapply a new wax topcoat afterward.

* Polyurethane and varnish are basically the same, although one is made with plastic resins and the other with natural resins. Both create a hard, waterproof coating that is impervious to most dirt and stain. Woodwork wearing these protective finishes may not look "natural," but it can be cleaned by simply wiping with a damp cloth.