Hi Mike,  Some years ago I asked the folks at the Smithsonian about
their antique pianos.  They said they never let the temperature fall
below 55 degrees F.  I figure they are a pretty reliable source of
information, so I've advocated 55 F. ever since.

My customer's home is one block from the Atlantic Ocean, and since it's
a rather leaky old shore home, I don't think 'too little moisture' will
be a problem.  (Until this summer, the piano was in a regular home in
N. Jersey where the environment was relatively 'controlled'.)

I'm thinking that if a regular blanket is put between the piano and
the electric blanket, and then another thin blanket is put over the
electric blanket, all it will do is keep the piano relatively warm over
the winter.

It's really the large fluctuations in temperature and humidity that
can damage a piano.  Yesterday I received an emergency call from a new
customer in N. Jersey.  They are having a concert today and their
regular piano tuner had tuned the piano just two days earlier.
Unfortunately, the tuning didn't hold.  (The piano is less than 20
years old.)

Upon testing, I found loose tuning pins.  I also found the piano on
an outside wall, near a heat radiator, and surrounded on two sides by
large single-pane windows (sun bearing).  This piano has obviously
suffered its entire life and the result is a weak pin block, cracks in
the soundboard, loose piano action, and poor tonal quality.

As they say, "The proof is in the pudding."  In the case of this
relatively new Yamaha grand, ignoring the commonly accepted environmental
conditions deemed appropriate for a piano has taken its toll.  I'm
hoping that the efforts I'm taking to protect the player piano "at the
shore" will help prolong the life of the 80-year old instrument, which
has been treated fairly kindly until its recent relocation.

You wrote:

> Air at 100% humidity and 0F (which is a generous assumption) has
> a relative humidity around 10% when heated to 55F.  This is the
> source of my concern.

Thanks, that compliments the information from Richard Vance.  He provided
formulas for determining the relative humidity at various temperatures.

Point is, it's pretty clear that an electric blanket is _not_ a good
way to keep the piano warm during the Winter.

Thanks again for your time, experiences and information.

Musically,

John A. Tuttle