Temp fluctuation affect?

[Mary Smith]

OK, Ray...so, why are soundboards dried in "hot boxes" before they 
are installed in pianos? And why do we install heater bars as part of 
Dampp-Chaser systems, if heating the air does not change moisture 
content of wood? Mind you, I'm not challenging your statements, I'm 
just trying to understand. Thanks.

>Sorry, guys.
>
>I've taught science too many years to accept that the relative humidity
>change has anything to do with the change in wood moisture content.
>Relative humidity changes as temperature changes, but the actual amount of
>moisture may indeed stay the same.  I understand all about dew point, etc.,
>but actual moisture content does not change because the relative humidity
>does UNLESS the temperature stays the same.
>
>A sealed container of air (or wood)may hold X amount of moisture.  If it is
>heated, its relative humidity goes down, because it is capable of holding
>more moisture at a higher temperature.  The converse is true upon cooling.
>True, wood being a solid, there is less difference caused by temperature
>than in air.  But the content doesn't necessarily change with the relative
>humidity reading which depends upon the temperature at which the humidity
>reading is taken.
>
>Ray T. Bentley, RPT
>Alton, IL
>
>Ready to retire this spring after 37+ years of teaching.
>
>
>----- Original Message -----
>From: <vem@email.byu.edu>
>To: <caut@ptg.org>
>Sent: Tuesday, January 22, 2002 3:12 PM
>Subject: Re: Temp fluctuation affect?
>
>
> > No, but the wood moisture content would change (be higher with a lower
>heat and
> > lower with a higher heat) because of the relative humidity change.
> >
> > - It's true that lowering the temp will decrease the relative humidity
> > - reading, but it will NOT mean that more moisture is present.  Relative
> > - humidity is just that...relative!  The absolute amount of moisture
>present
> > - will not change solely by lowering the temperature.
> > -
> > -
> > - --
> > - Ray T. Bentley, RPT
> > - Alton, IL
> > - ray@bentley.net
> > - www.ray.bentley.net
> > -
> >
> > vince mrykalo
> >
> >
> >