[CAUT] Reading low humidity (was seasonal SB failure)

[Fred Sturm]

On 3/3/06 4:18 PM, "Ron Nossaman" <rnossaman@cox.net> wrote:

> 
> 
>> "Wood with very low EMC will absorb ambient high RH very
>> quickly. It's slower to dry out, and it takes higher temps and airflow to
>> speed that process (read institutional conditions <g>). I can measure RH
>> easier than EMC, and RH is good at predicting what will happen in the near
>> and long term future."
>> 
>>         I gain from this that wood reacts very quickly on the intake and
>> very slowly on the release.
> 
> Not so. I've seen it assumed a lot of times, but have never
> been able to find documentation to that effect from even a
> minimally authoritative source. Both absorption and release of
> moisture in wood is proportional to the difference between
> wood MC and atmospheric RH%.
> 
> Even so, keeping track of RH% readings is a very good
> practical method of anticipating what the instruments'
> reactions will be with the resulting MC levels, which are
> lagging somewhat behind the RH% changes.
> 
> Ron N
> _______________________________________________
> caut list info: https://www.moypiano.com/resources/#archives
> 
My experience leads me to this conclusion based on pitch change speed.
Maybe, though, it is because I more often experience sudden spikes up, due
to rain, while the drops in RH are more gradual. If somebody regularly takes
a piano from a humidity controlled space onto a dry stage, and is able to
track what happens over the course of, say, 24 hours, together with the data
for RH on stage and RH in the controlled space, I would be very, very
interested to know what is observed.
Regards,
Fred Sturm
University of New Mexico