Pianos and Humidity

As a piano technician I'm asked fairly regularly why a given piano goes out of tune, or why the tuning didn't last very long. Although I've mentioned humidity on my website's FAQ, I thought I'd expand a little here. 

More than any other factor, piano tuning stability is tied to ambient humidity. Wood is hygroscopic, that is, it expands and contracts relative to higher and lower humidity. Tension on the piano strings rises and falls with expansion and contraction of the wooden, hygroscopic sound board.

Much of the piano is made from wood and it all reacts to swings in humidity. Expanding and contracting wood will ultimately result in cracks, warping, twisting and glue joint separation. High humidity is also a favored environment of mildew and rot. Furniture finishes to some degree are also affected by varying humidity.

I live and work in the Toronto, Canada area. This region has wide seasonal swings in humidity. I regularly measure15% in the winter to 80% in the summer. As far as climate is concerned, Toronto is not a friend of pianos.

Piano technicians (including me) recommend the use of reliable humidity control systems to prevent long term damage while providing shorter term tuning and performance benefits.

You can do your piano a great favor (and all of your wood furniture and floors for that matter) by optimizing your home's humidity. If you have humidity control as part of your built-in climate control system, ensure that it is properly regulated and maintained. It's also possible to add such capabilities if your home system doesn't already have it. Stand-alone humidifiers and dehumidifiers are another option but all of these approaches need to be monitored and maintained as part of your household routine.

The most of effective solution for humidity control is an in-piano system. Most technicians are happy to install these at a reasonable cost. That cost is eventually offset by less frequent tunings, and reduction of repairs due to humidity. Compared to the purchase price of even a moderately priced piano, an in-piano humidity control system is a very affordable investment.

Phil Manning - Piano Technician

Owner/Operator of Artist Piano Care