The beauty of French polish comes from the layers and layers of polish that have been used to build up a deep lustre. When cleaning, you remove the dirt and old wax from the top layer of polish, and you must take care not to damage the actual French polish finish. Never sand French polish or use undiluted white spirit or other solvents, or you may end up having to refinish the whole surface.
Wipe the surface gently with a clean cloth and warm water containing a very small amount of soap. Use water sparingly. Dry with a soft, dry cloth. This should remove surface dirt.
Mix a solution of white spirit and linseed oil in a 10:1 ratio and apply liberally to the surface. Leave for two minutes, then wipe off with a clean cloth.
Gently rub the surface with very fine steel wool dipped in the white spirit and linseed oil solution, following the grain, to remove any of the remaining dirt. Wipe any residue off with a soft cloth before it dries.
Rub with a dry cloth and then wax with a good quality beeswax, making sure you thoroughly wipe off the wax afterward.
Clean French polish gently. If you are too vigorous, you may damage the polish and will have to refinish with a coat of French polish. Dust the surface first so small grains of dirt and grit do not get under the polishing cloths and scratch the surface. Use a soft toothbrush to get into corners and mouldings. Remove tiny paint spots by flicking them off with a penknife or your fingernail. Do this carefully so you are simply breaking the adhesion between the spot of paint and the top layer of polish and not damaging or gouging into the polish itself.
Measure the white spirit solution carefully as too much white spirit will dissolve the French polish. Do not be tempted to use white spirit undiluted as it will take the polish off.