Why keys need more care than the rest of the piano

Of everything on a piano, the keys take the hardest knocks. They are the only part most players ever really touch, and they collect everything the hands bring with them — natural oils, hand cream, sun cream in summer, the residue of a biscuit eaten an hour ago, and a fine film of household dust that settles whenever the lid is left open. Multiply that by two or three players a day and you can see why keytops lose their sheen long before the strings or the hammers show any sign of wear.

The good news is that key care is simple, cheap and quick. The bad news is that one careless product can do permanent damage in seconds. If you take only one thing from this article, make it this: mild soap and water, used sparingly, is all a piano key ever needs. Alcohol, solvents and abrasive creams have no place anywhere near a keyboard.

The golden rule: nothing harsh, ever

Ivory and the modern plastics used for keytops are both softer and more porous than they look. They scratch, cloud and craze easily, and once a surface has been etched or dulled, no amount of polishing will bring it back.

• Never use alcohol, methylated spirits, white spirit or acetone. These strip the surface, leave white bloom marks and can lift the edges of ivory veneer.
• Never use abrasive cleaners or scouring pads. Cream cleaners, cream polishes and kitchen scourers grind away the fine finish.
• Avoid vinegar, lemon juice and citrus sprays. Their acidity attacks both ivory and older plastics over time.
• Skip furniture polish and silicone sprays. They leave a slippery, greasy film that transfers straight to your fingers.
• Never spray anything directly onto the keys. Liquid runs down the sides, into the gaps between keys, and onto the balance pins and felt bushes underneath.

If a product label says "streak-free shine" or "antibacterial", it almost certainly contains something you do not want on a keytop.

Everyday dusting: two minutes, once a week

Most key problems start as dust. Dust holds moisture against the surface and, mixed with hand oils, forms a grimy paste that works its way into the gaps. A soft microfibre cloth is the best tool you can own — it lifts dust rather than pushing it about, and it leaves no lint behind.

• Close the lid whenever the piano is not being played. This single habit prevents most of the build-up.
• Wipe along the length of each key, from the back towards the front, following the natural line of the key.
• Use a separate, dry, soft brush for the gaps between keys — a clean make-up brush or a soft artist's brush works beautifully.
• Never use a feather duster. It simply moves dust into the key bed.
• Wipe the black keys with the same care as the white ones; they scratch just as readily.

Wiping with mild soap — the sparing method

For sticky marks, fingerprints and general grubbiness, a barely damp cloth is the answer. Fill a small bowl with lukewarm water and add one or two drops of mild washing-up liquid or a gentle hand soap. Dip the microfibre cloth, then wring it out until it is almost dry — no drips, no visible wetness.

Wipe one key at a time, working along its length. Then immediately dry that key with a second, dry cloth. Never let the moisture sit, and never wipe a whole octave and dry it afterwards. Work in small sections: clean, dry, clean, dry. Use a fresh, clean cloth rather than one that has been near polish or detergent, and change the water if it starts to look cloudy.

Finish by drying the fronts and the small strip of key between the black keys where moisture likes to linger.

Telling ivory from plastic, and treating each well

Pianos made before the mid-1950s very often have genuine ivory keytops; most instruments built since have plastic. You can usually tell by looking closely at the surface: ivory shows faint, irregular grain lines and often a warm cream or yellowed tone, while plastic is uniform and slightly cooler in colour. Ivory also feels marginally more porous under the fingertip.

• Ivory is hygroscopic — it swells and shrinks with humidity, which is why old ivory keys chip and lift at the edges. Keep moisture to an absolute minimum, dry immediately, and keep the room between roughly 45 and 65 per cent relative humidity.
• Plastic is more forgiving but can be clouded by alcohol and scorched by direct sunlight. Keep the piano out of direct sun, which also yellows ivory unevenly.
• Both types dislike heat. Never place a piano against a radiator or in front of a sunny window.

Habits that save your keys, and when to call a technician

Wash and dry your hands before playing, and keep food and drink well away from the instrument. Trim long nails, remove rings that catch the key edges, and think twice before playing straight after applying hand cream or sun cream.

Some jobs belong to a professional. Lifting, chipped or missing ivory, keys that stick or fail to return, a crunchy feel under the finger, or residue from sticky tape should all be left to a piano technician — ideally booked alongside your next tuning, when the action is already accessible. Between visits, keep the lid closed, dust weekly, wipe sparingly, and dry immediately. Your keys will reward you with decades of smooth, quiet response.