According to The Piano Technicians Guild, modern pianos have either traditional lacquer or modern polyurethanes/resins style finishes. Simple weekly cleaning and maintenance can do wonders for a piano that has a black lacquer finish. Use caution applying certain cleaning products to black lacquer, as it can strip the piano of its beautiful sheen and shine. Apply only mild soaps and furniture polishes to remove fingerprints and smudges. Check with your piano's owner guide if you are unsure about the proper cleaning agents to use on your piano.
Dust the piano with a microfiber cloth or a feather duster. Dampen the microfiber towel with water (adding in mild soap or ¼ cup of baking soda is optional) and wipe down all of the piano's areas in long, straight strokes. Do not wipe down piano in vigorous circular motions because it will cause the finish to scratch.
Polish the piano. Allow for the piano to dry thoroughly before applying a lacquer finisher. Use a gloss-producing polish on the piano to enhance sheen. According to the Piano Technicians Guild, suitable polishes for black lacquer pianos are Guardsman Furniture Polish and OZ Cream Polish.
Always avoid hard pressure rubbing on the piano's sharp corners and edges, as finish can easily strip and scratch.
Dust and wipe the black lacquer finish with mild soap and water on a weekly basis to maintain its appearance. Refrain from using paper towels or pretreated furniture polishing cloths to wipe up sudden spills or smudges, because they can scratch the piano's finish.