How to keep an upright piano in tune through seasonal changes

Why British seasons unsettle an upright piano

An upright piano looks like a piece of furniture, but it is really a wooden instrument under enormous strain. A typical upright carries many tonnes of tension across its strings, and all of that tension is balanced against a soundboard made from thin spruce. Spruce is hygroscopic: it takes moisture from the air and gives it back. When the air is damp, the soundboard swells very slightly, pushing the strings sharper. When the air dries out, the board shrinks, the strings slacken, and the pitch sinks.

Britain gives our pianos a particularly testing year: damp autumns, centrally heated winters that dry the air to desert levels, humid summers and sudden cold snaps. A swing from 70% relative humidity in October to 30% in January is enough to drag a piano noticeably flat, often by a quarter-tone or more, and to leave individual notes drifting out of tune with their neighbours.

Find the piano's comfort zone

Most instruments are happiest at a relative humidity of about 45–65% and a temperature of roughly 18–21°C, held as steady as you can manage. You do not need laboratory conditions, but you do need to avoid extremes and, above all, sudden changes.

• Place an inexpensive hygrometer on top of the piano and check it weekly through autumn and spring.
• Position the piano on an interior wall, away from radiators, windows, external doors and open fires.
• Keep it out of direct sunlight and away from draughts.
• Leave a small gap behind the piano for air to circulate; never press it tight against a cold, damp outside wall.
• Think twice before putting a piano in a conservatory, cellar, garage or steamy kitchen.

Watch for the early warning signs

Pianos rarely fail without notice. They whisper first, and a little attention now saves a great deal of expense later.

• Unisons that shimmer or beat, especially in the middle of the keyboard.
• Octaves that sound wobbly rather than clean.
• Keys that feel sluggish, heavy or slow to return — a classic sign of damp swelling the felt and bushing cloth.
• A new buzz or rattle on certain notes.
• Rust on strings, or green verdigris on copper bass windings.
• Tuning pins that turn too easily when your technician works on them.

None of these mean disaster. They mean the instrument is telling you something, and usually something that is straightforward to put right.

Autumn and winter: defending against dry heat

Central heating is the single biggest cause of winter tuning drift. As the radiators come on, the air in a living room can fall below 30% relative humidity, and your piano begins to dry out within days.

• Run a room humidifier nearby, or ask your technician about a piano humidifier fitted inside the instrument.
• Turn the radiator in the piano's room down a notch and keep the door open so warmth is shared.
• Keep the top lid closed and the fallboard down when the piano is not being played.
• Avoid standing bowls of water inside the piano; a spill does far more damage than dry air.
• If you use a full dust cover, lift it occasionally — a cover can trap damp air against the case during a mild spell.

Wait until the heating has been running steadily for a couple of weeks before booking a winter tuning. Tuning a piano mid-change is a losing battle.

Spring and summer: managing the damp

As the weather turns soft and muggy, the problem reverses and the piano risks swelling instead of shrinking.

• Use a dehumidifier in the room during humid spells, and empty it regularly.
• Ventilate on dry, breezy days rather than wet ones.
• Watch for condensation on windows and cold walls near the piano.
• Check gutters, roof tiles and window seals above the instrument; slow drips are quietly catastrophic.
• Never stand drinks, vases or houseplants on the piano.

Summer is also the season for open windows and garden doors. A piano sitting in a through-draught will drift, so move it clear of the main airflow if you can.

Simple habits that keep tuning stable

Play the piano. Ten or fifteen minutes most days keeps the action moving, circulates air around the strings, and lets you hear a drifting unison before it becomes a nuisance. Beyond that:

• Have it tuned twice a year, ideally in spring and autumn when the seasons turn.
• Move it as rarely as possible; every shift disturbs the structure.
• Dust the soundboard gently with a soft brush or a vacuum brush attachment, never a damp cloth.
• Clean keys with a barely damp cloth and dry them immediately; keep sprays and polishes away from the action.
• Let a brand new piano settle for two to four weeks before its first tuning.
• If it has dropped a long way, expect a pitch raise — two visits, the second a few weeks later.

Call your technician if the drift is severe, if keys are sticking, or if you hear a new buzz. A good tuner does more than tune: they check the action, watch for cracks and loose pins, and warn you about problems while they are still inexpensive to fix. Looked after with a little patience, an upright will hold its tuning far better than most owners expect, and will reward you with a warm, even tone right through the year.