A piano is a machine and like all other machines it will

periodically need maintenance. It is a special type of machine

made of organic materials such as wood, felt and leather. Unlike

most machines that are made of metal or plastic or both which are

fairly rigid, pianos are far more temperamental. If it is raining, the

humidity will be higher and the keys may become sluggish. If it

becomes especially dry, the soundboard wood will shrink and the

pitch will go flat.

Every piano owner should own a hygrometer. It is a device that

measures the relative humidity (RH) in the location it is placed.

Usually it is also a thermometer, but it may not be depending on

the type purchased. This handy device should be kept on or near

the piano at all times. Pianos like it best at about 45% RH. If it is

below 20% there is a risk that the wood will crack and expensive

repairs may be on the horizon. If this applies to your situation,

purchase a humidifier. Anything above 60% RH and the strings

will rust faster and the finish on the cast iron plate (also known as

the harp) will chip and it will rust too. If this applies to your

situation, purchase a dehumidifier.

The main reason a piano goes out of tune is because the

soundboard changes shape in response to changes in temperature

and humidity, whether it is played or not played. Pianos should be

tuned twice a year, every six months. If a piano is not tuned for

more than a year, there is a possibility that it will need a pitch

raise, a major adjustment in string tension, before it can be tuned.

The longer it has been between tunings, the more likely it will need a pitch raise.