Plastic tops can be cleaned with a soft cloth and a mild solution of dishwashing detergent and warm water, cloth fully wrung out. If the dirt is caked on, use rubbing (70%) alcohol unless the key tops were painted (you may encounter this on some old pianos—be careful). Some technicians report good results with Simple Green®. Degreasers like 409 may be too aggressive and may dull the surface.
Porous tops, including ivory and cow bone, can be cleaned with a product such as Cory Key-Brite™ or Yamaha keytop polishing paste. Some people recommend a whitening toothpaste, but there may be long-term effects from the toothpaste residue. You can use alcohol to clean caked-on dirt. Don’t use it regularly, though, because it will dry out the ivory and make it absorb even more dirt. Don’t use vinegar, lemon juice, or other acidic products; they will etch the surface.
Ebony sharps are usually stained or painted, and may become discolored if cleaned with an aggressive cleaner (ebony is a dark wood, in which lighter streaks may appear). Clean a buildup of dirt with rubbing alcohol; otherwise, wipe the key tops with a mild solution of dishwashing liquid and warm water on a soft cloth fully wrung out.
Dusting: Dust all reasonably water-resistant finishes, such as lacquer, varnish, and polyester, with a cloth lightly moistened with water and fully wrung out. A moist cloth picks up particles of dust more effectively than a dry cloth, and is less likely to scratch the surface. For dry dusting, use a dusting brush or gently wipe the surface with a soft cotton fabric.
Cleaning: To remove finger marks, dirt, or a buildup of waxes and polishes, use a silicone-free furniture-cleaning fluid. For light cleaning, you can use a mild solution of soap in water: add a few drops of unscented liquid soap or dishwashing liquid to a quart [liter] of warm water and stir thoroughly. Moisten the cloth, wring it out completely, dry it a few minutes, then wipe the surface.
Polishing: After cleaning the surface, you may want to enhance it with furniture polish. Use a polish that doesn’t contain silicones. Apply it with a buffing/polishing sponge or a lint-free cloth of soft cotton.
Maintaining a high-gloss finish is challenging because even dusting scratches it. Although the polyester finishes found on most European and Asian pianos are more scratch resistant than lacquer or varnish, fine scratches and swirl marks show clearly on polyester’s glossy surface. There are two approaches to maintaining a high-gloss finish. One is to periodically apply a product that hides scratches (most conventional furniture polishes do that); the other is to buff out the scratches. Some products do both.
To buff out very fine swirl marks or scratches and to enhance the clarity of the surface, first apply a product like Meguiar’s Mirror Glaze® Plastic Cleaner No. 17 with a clean, damp buffing pad or fine sponge applicator, let it dry for 5 to 10 minutes, then wipe it off with a very soft, clean, dry cloth (such as a soft baby flannel). Repeat this using Plastic polish No. 10. Synthetic sponge applicators are available in auto-parts stores and paint suppliers.
Rubbing: Scratches in a lacquered satin finish (found on most American-made pianos) can be removed by rubbing the finish with steel wool, but this is best left to professionals.
Various devices for cleaning the soundboard are available— search “piano duster” on the Web. You can improvise a duster by affixing a cloth to a flexible rod or “soundboard steel,” available from piano suppliers. The most effective tool for cleaning the soundboard under the plain strings is a brush with long, natural bristles. Hold a vacuum nozzle in the area you are brushing to avoid spreading the dust around.
I prefer removing dust between tuning pins by vacuuming them with a long-bristle brush attachment on a vacuum cleaner hose. If the bristles are not long enough, loosen the dust with a paintbrush and hold the vacuum hose next to it. Don’t use any liquid or paste cleaners on or between the tuning pins—they could corrode the strings and tuning pins, and damage the plate gilding and pinblock.
In more recently made pianos, pedals are coated with a clear finish to prevent them from tarnishing. Polishing finished metal requires stripping the finish. If the pedals are not finished, use a quality brass polish such as Brasso, or the Flitz Metal Polish, available from piano-supply houses.