[CAUT] curious...

[Roger Jolly]

Hi Gerald,
                  The sound board if the first to react, not a lot of mass, 
and normally spruce, The back support reacts much slower assuming a maple 
liner and much more mass.
The sound board will show changes much more quickly, 2 or 3 cents on stage 
within a hour, not too uncommon depending on stage lighting etc.
The spruce is much more porous than the harder woods, and will absorb and 
give up moisture much more quickly.
As Ron mentioned spot humidity checks will not tell you much.
I wish we had 18% at this time of year. Right after Xmas break try 8% for 
dryness. That's plus or minus 20% with my equipment at this range.

Regards Roger



At 01:15 PM 1/29/2011, you wrote:
>Hi Ron,
>
>We both basically have the same type of weather.  With Calvin College,
>generally in August, the RH is 65% +.  September it's in the lower 60% to
>mid 55% RH range.  By November it's usually at least around 30's % RH and by
>the first of Dec it's usually around 25% RH or less.  By the end of
>December, it is often in the 18 % RH range here.
>
>During this whole process of weather changes and RH changes, especially this
>year, going from August through December, the piano is drying continually,
>little by little consequently also going flatter, little by little.  My RH
>went up this month too in some of the rooms to as much as 35 %.  While in
>other rooms, it was only at 17 or 18% RH.  All of the pianos regardless were
>still flat.  Some flatter than others but, nonetheless, they were still all
>flat.
>
>I believe because of the constant drying since August and probability that
>your December was likely similar to mine with a lower RH toward the end of
>the month, that the piano will not go up in a short amount of time but
>instead will continue to go flatter because of a shrinking sound board (and
>other reasons) since September or so.  It's been drying out for months
>already whereas, the RH has only gone up briefly.  It will go back down
>again as the temp outside also goes down and the heat in our buildings
>continues to stay on for longer periods of time.
>
>At least, that's my theory!
>
>Jer
>
>-----Original Message-----
>From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Ron
>Koval
>Sent: Saturday, January 29, 2011 12:44 PM
>To: caut at ptg.org
>Subject: [CAUT] curious...
>
>
>I've noticed something curious over the last couple of weeks on many of
>my institutional tunings.  The pianos are starting out a little flatter
>than would normally be expected considering the snapshot of RH that I
>record.
>
>Here's an example from a Yam p22 in the college choir room
>
>Tuned early sept 60%RH
>late sept 49%RH - ave 5cents low
>early dec 29%RH - ave 20 cents low
>
>all of the above reflects what I normally see.
>
>today 31% RH - ave 10 cents low...
>
>I guess a data-logger might provide more info.
>
>Anyone with educated guesses???
>
>Ron Koval
>chicagoland
>                                           =