(This article originally appeared in the Winter, 1991 issue of the Journal of the American Harp Society,
Vol 13, no. 2
By Carl Swanson

     With the unfortunate passing of John Escosa, we now welcome Carl Swanson to the staff of the Journal to continue the harp maintenance column started by John five years ago.

      Carl has extensive training as a harpist, having received both bachelor’s and master’s degrees in harp performance in addition to three years’ private study with Pierre Jamet. He is a partner in Boston Editions and has published several transcriptions for harp. For the past 15 years he has been an independent harp technician, focusing primarily on structural restoration of pedal harps. His book, A Guide for Harpists has become a standard reference for harp maintenance and minor repairs. Carl is founder and president of Swanson Harp Co., a new pedal harp manufacturing company and repair facility. –Ed.(Jane Weidensaul)

     For my debut maintenance column I have decided to harp (appropriately enough!), harangue, and bellow on a subject dear to my repairman’s heart.

     But first, let me ask you this. If someone came to you, told you that he had just bought a brand new harp, and asked you what was the most important thing for the health of the new instrument, what would you tell him? Tune it every day? You’re not even close. Keep it away from windows? you’re getting colder. Keep it nice and warm in the winter?
Disaster looms!

     The correct answer is(may I have the env elope please…): Humidify! Or to be more precise, control the relative humidity in the room where the harp spends most of its time.

    Why is this so important? Because your harp is made of wood, and wood expands in a more humid environment and contracts in a drier one. The wood in your harp was initially dried to a 6% to 8% moisture content prior to construction, and ideally it should remain there, with as little fluctuation as possible, for the life of the instrument.

     Higher humidity will swell wood fibers, causing them to compress. Extreme high humidity over a long period of time will attack the glue, causing joints and laminations to separate. It can also grow mold on the instrument. A damp basement or an unairconditioned house in one of the Gulf states could become this humid, and here a dehumidifier is called for.

     Lower humidity on the other hand shrinks the wood fibers, causing the wood to crack and joints to open up since the now smaller wood fibers can no longer cover the area they originally did. So it is low humidity which plays havoc with harps.

     In order to maintain a moisture content of 6% to 8% in the wood, the relative humidity of the air must be kept at 45% to 65%. Hot air can hold more water than cold air. If you want to raise the relative humidity of a room, you must either evaporate water into the air or lower the temperature. If your harp spends any part of the year in a heated room, or where the relative humidity drops below 45%, you must humidify.

     This can be done by a combination of lowering the room temperature(under 70° F is good, under 65° F is excellent) and using a humidifier.      

What kind of humidifier?

     This is extremely important, so read carefully! There are three types of humidifiers, and only one is appropriate for wooden musical instruments.

     Cold water evaporators have a tank full of water and a porous belt that is rotated into the tank, soaking it with water. When it rotates out of the tank, a small fan blows air through it, evaporating the water and sending humidified air into the room. This type is the only one to use! There is no visible mist or steam, only fully evaporated water. It should be placed next to your harp because the humidity will be highest close to the machine.

     Electronic humidifiers and vaporizers(like Mom used to use when you were a kid) both break water into tiny droplets which are then dispersed into the room in the form of a visible mist. Some of these droplets will evaporate, but most simply drop to the ground or float around until they land on something(such as your harp). If the water is hard, these droplets will also leave a calcium deposit. Several months of this will result in a white haze on everything in the room. Do not use electronic humidifiers or vaporizers. Wood doesn’t dry out the second the relative humidity drops. The process takes several days or more. So even if you move your harp constantly, returning it to a humidified room as often as possible will keep it healthy.

     If I haven’t yet convinced you(how could this be possible?) think of it this way. Your current harp would cost anywhere from $1,500(non-pedal) to $25,000 to replace. Are you really too poor to spend another $100 to save its life?