Harps and Humidity
How to Keep Your Harp Safe – Whatever the Weather
40-50% relative humidity is considered a safe range for harps and other solid-wood instruments.
But what does that mean for harpists and what can they do about monitoring and controlling the harp’s environment?
Wood is an organic material which swells and contracts depending on its moisture content. Wood exchanges moisture with the surrounding air, so its moisture level depends directly on the moisture in its immediate environment.
As harpists know, when a harp contracts and expands its tuning will change. It can also be a cause of string breakage. However, wood shrinkage and contraction can also have a seriously detrimental effect on the structure of the harp.
When the surrounding air is dry, the harp contracts and as it gets smaller, parts of the instrument such as the joints and seams are under tension. At this point, cracks may develop and joints split. When the surrounding air is too humid, the wood of the harp swells and so joints and seams can also fail. In addition, at high humidity levels wood loses its resistance to bending. This can result in permanent distortion to shaped parts of the harp such as the neck and soundbody. Wood gains weight as its moisture level increases and this in turn affects the tone of the instrument: too much weight results in less responsive tonal chambers and a dull sound.
Extra strain can by put on a harp by rapid changes in its moisture level. This is a concern in a variable climate such as the UK’s, where ambient temperature and the use of central heating can result in rooms undergoing significant changes in humidity within short periods of time. Likewise, taking the harp outside can have a dramatic effect on its moisture levels. Winter is a particular concern as cold air is very dry, so cracks can occur as the harp shrinks. Of course, it is often necessary to take the harp outside in winter – just be sure to limit the time spent in the cold outside air as much as possible, avoiding leaving the harp in the car overnight, and be very careful not to put the harp near a source of heat when you bring it inside.
So now you know what happens to wood in extremes of dryness and humidity, but what can you do about it? First, you need to know the humidity level in the room where your harp is kept and for that you can use a hygrometer, which is an electronic device which monitors the humidity and temperature of the environment. We sell these in our shop and on our website.
If your hygrometer shows that the room is too dry, you can use a humidifier to replace moisture. Likewise, a dehumidifier will reduce humidity levels. You are aiming for a reading of between 40-50% humidity. One tip is to place the hygrometer as far away from the humidifier/dehumidifier as possible, otherwise it will be taking it readings from the air that has just been processed by the unit and will show false results.
Being aware of how wood responds to moisture and what to do about it can help you to protect your harp from potential cracks and distortion. If you are concerned about your harp because it is showing signs of cracking or distortion, you can bring it to our monthly servicing studios, where our professional harp technicians will be able to advise you.
Posted on: January 2, 2014.