Disklavier

In reply to James:

> I'm in the UK - is the 42% relative humidity the same around the world, or
> different for the various markets (because of the way the wood is
> treated)?
>
> Should I be doing anything to my upright disklavier to preserve humidity?

Moisture control is the bane of existence for anything made of wood -
especially wood under tension and compression like a piano soundboard, or
piano case and action parts where a constant dimension is required (warp
prevention), or preventing the lanolin in wool felt bushings and piano
hammers from drying out.  Too much moisture and too little moisture will
damage the piano over time.  Two factors to be considered are Relative
Humidity (RH) and moisture content of the wood.

The ideal Relative Humidity around  a piano should be a constant 42%RH.
Constant is the important concept here, so don't worry if your numbers are a
little higher or lower.  Dampp Chaser brand climate control systems equipped
with humidistats and heating rods do a great job keeping excessive moisture
out of the piano by burning off the moisture before it soaks in.  I am more
skeptical of the value of installing the humidifier tanks, though, on these
systems.  Definitely NOT a good idea to have a tank of water next to the
electronics!!!!  If you have an upright Disklavier, have the system
installed on the outside back of the piano with the humidifier tanks and
cover.  For grand piano Disklaviers, have several shorter rods only (no
water tank!) installed underneath the soundboard with a humdistat to avoid
going across the speakers and amplifier.

Adding moisture to air in a room with a Disklavier is more problematic.
Installing a "whole house" humidifier like an April Aire system is very
effective for homes with gas forced air heat.  However, homes with heat
pumps don't produce hot enough air for the water to vaporize, so the water
must be heated first. Where I live there are a lot of minerals in the water,
so heating elements crud up very quickly and humidifier pads quickly
calcify.  If using a room humidifier, make sure it is at least 20 feet away
from the piano. Humidifiers are high maintenance no matter what the
situation - whether keeping the water tank filled or replacing or cleaning
the evaporating mechanism.  Because of this maintenace issue it doesn't get
done often enough to maintain a constant moisture level.

In real life, constant humidity control seldom exists. Evaporater pads on a
furnace humidifier system should probably be changed every month or two
during the winter.  Room humidifiers are not filled two or three times a
day.  Doors and windows get opened when the temperature is comfortable.
Running the air conditioning is thought to remove an adequate amount of
moisture.

Here in the U.S. many people heat their homes during the winter so it is
comfortable to wear only a T shirt instead of a sweater.  That means the RH
in many North American homes gets down to 10%.  On the other hand, I could
have pushed my piano outside onto my deck yesterday and it would have dried
out in the 29% RH.  When we lost power for 5 days during the huricane the
living room was reading 93% RH.  Needless to say these conditions are more
favorable to making a living as a piano tuner than they are for preserving
the dimensions of a piano!

This climate fluctuation also has a great effect on  piano manufacturing.
To prevent warping of the wood pianos made for the North American climate
both inside and outside, wood must be kiln dried to a 5% moisture content
before manufacturing a piano. This is expensive.  For Europe and Asia, the
climate both outside and inside is more even.  Wood naturally dries to a 12%
moisture content given enough time, and that is cheap to do.  Hence, we have
the definition of the Gray Market piano - one manufactured for a different
climate than the one it is being sold because market factors of supply and
demand as well as price make it look cheaper.  The sales price may be
cheaper but you will constantly be paying for tuning and regulation because
all the wood in the piano is constantly changing dimension!

I realize that my opinions concerning climate control for pianos and
Disklaviers may not agree with other piano technicians, but then again I am
not making a living selling humidifier tanks!

Carol Beigel