Soundboard Moisture Content

[Delwin D Fandrich]

> -----Original Message-----
> From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On
> Behalf Of Greg Newell
> Sent: March 30, 2004 12:56 PM
> To: Pianotech@ptg.org; MPT@philbondi.com
> Subject: Soundboard Moisture Content
>
>
> Can anyone give me an idea of the normal moisture content of a
> soundboard?

There is no "normal" moisture content for soundboards. It depends entirely
on the temperature and humidity conditions immediately surrounding the
piano. The MC changes along with the climate changes.


>
> The current conditions are Northeast Ohio older home but fairly well
> insulated. The heating system adds moisture to the room via an April air
> type unit in the forced hot air furnace. The piano is a roughly
> 10 year old Petrof. The weather lately is normal spring type weather for
this region
> i.e. 35-55 ish degrees with off and on rain. The customer used a pin type
> moisture meter on his own soundboard and reported a 21% reading.
> Have any of you taken readings directly on the board with either
> a pin type or a pin-less type meter ad compared them to the Hygrometer
> reading some of us normally take? Would it be useful information to obtain
these
> readings?
> If you were buying one for the main purpose of measuring boards would you
> buy pin type or pin-less? Why?
> Thanks in advance for your inut.


Neither type of moisture meter is going to give very accurate readings on a
finished soundboard as installed in a piano. Partly because the panel is so
thin and partly because it is finished.

It is unlikely that the soundboard in question has a MC anywhere close to
21%. For a soundboard panel to reach a MC of 21%, assuming the temperature
in this home is between 60ºF and 80ºF, the relative humidity would have to
be something in excess of 90%. Unlikely, unless the house is equipped with
steam generators. In other words, with the outside conditions you indicate
it would be pretty difficult to achieve this.

The best way to determine the MC of a soundboard is to monitor the
temperature and relative humidity and determine the equilibrium moisture
content by referencing a chart such as that found in The Wood Handbook. More
likely the MC of this soundboard is in the 7% to 10% range.

Del