Remove loose dust and dirt by wiping surfaces with a cloth slightly dampened with a solution of 1/4 cup oil soap diluted in 1 gallon of warm water. Repeat the process, changing the water as necessary, until all loose dirt is removed. Let it dry.
Wipe a thin coat of gel cleaner on a small surface area with a soft cloth, rubbing gently in a circular fashion. You will immediately see black or brown grime on the cloth.
Wipe the surface dry with another clean cloth.
Repeat the process one section at a time, redoing surfaces until you achieve the cleanliness desired. Carved details and crevices can be gently scrubbed with an old, soft toothbrush.
Wipe all surfaces with clean cloths until all gel and dirt are removed. Let the piece dry and then use a paste wax to restore shine, if desired.