Piano On Ice.

[Baldwin Yamaha Piano Centre]

Danny Moore wrote:
> 
> NBWW@aol.com wrote:
> 
> > I have this theory that as the temperature goes down, the humidity goes up,
> > thus the piano sits in a relatively stable environment. It may be -10 degrees F
> > outside but thr relative humidity can be
> > as high as 70 %.
> 
> Could you expand on that theory please?  I had always assumed that the relative
> humidity approached 0% as the temperature dropped below freezing since any
> moisture that had been in the atmosphere would be frozen and thus removed from
> its vaporous state.  This should remain true inside a non-heated building as
> well.  It seems that the only humidity would be a result of the heating of a
> building for short periods of time, say for Sunday services, which would result
> of condensation as a result of the radical temperature change.
> 
> Those of us here in the swamp are not familiar with that since (1) it only
> freezes about once every 5 years and (2) we rarely see the relative humidity drop
> below 80%.  All comments and observations are welcomed.
> 
> Regards from the land of mold, mildew and allergies.
> 
> Danny Moore
> Houston Chapter
Hi Danny,
          Here in the far frozen north our winter temperature gets below
-40 degrees but the RELATIVE humidity can be 80%. If you were to warm up
a cubic meter of that air to 70F the RH or RELATIVE humidity at that
temperature would be almost non exsistant.   The key word here is
relative, The 100% RH is the maximum amount of water vapour the a given
amount of air can hold, once you reach that point it either rains,
hails. or snows. Commonly refered to as the dew point. Piano wise we
encounter different problems than you would encounter in the swamp
lands. Cracks rattles loose pinning due to shrinkage ect.  Green centre
pins for instance is a sure sign that the piano has not spent its life
in the hinterland.  As a piano warms up, the warm air has a higher dew
point and no doubt a resonable amount of RH. Therefore when this
moisture laden air comes in contact with the cold object the temperature
drops past its dew point hence the condensation.  To avoid this
condensation when we uncrate pianos in the winter we wrap them in thick
moving blankets right to the floor and leave them for 48Hrs. I have
uncrated pianos that have been exposed to extremely low temperatures and
seen them turn white with frost in minutes. The piano was so cold that
two things happened, First the dew point was passed to create water
second the object was so cold that it immediately froze the water.
  I think I remember Damp Chaser had a nice little blurb that explains
RH and dew points ect. Or maybe You can find a basic physics book that
covers the complete subject Altitude also has an effect.
Hope this helps
Roger