Soundboard Moisture Content

[Richard Brekne]

Greg Newell wrote:

> Thank you Del ( and congrats). I appreciate your quick response.
> I've been thinking of a purchase but what I understand you to say is 
> that no meter will give a reading likely to be accurate enough to 
> warrant the purchase. I was hoping to have something for shop use as 
> well and also something to show a customer. The likely scenario is 
> that I encounter this Petrof or similar piano/situation with the 
> compression ridges and can then point to an unusually high reading on 
> the meter suggesting that there are problems somewhere contributing to 
> this phenomenon. Could you tell me how you address this kind of a 
> situation?


Your best indicator that is handy is to familiarize yourself with the 
correlation between RH, temperature, and MC.  This will give you 
accurate enough information to make the kind of diagnosis you are asking 
for.  Del suggested the Wood Handbook and I can re suggest that too you. 
I bought it after his prodding me to do so for some time, and its got 
tons of good information in it that is good for pianotechs to know

Petrofs use compression crowned soundboards, and that means you 
definantly want to inhibit the local RH from getting too high. Doing 
exactly that is the only real option for dealing with the situation.

As far as your customer and his dohicky is concerned... if you can 
simply point to a well recognized authoritive book on the matter, and 
show him that a give RH at a given temperature yeilds such and such a MC 
.... no ifs ands or buts about it.. then you can also demonstrate to him 
that his apparatus is in error and should be trashed.

Typical situation really... where a customer is armed with just enough 
information and tools to cause problems, but not enough to sort them out.

This, in itself, is no biggie Greg.

> I am in the rather sticky situation of having recommended this piano 
> for purchase to this customer. They bought it second hand from another 
> of my customers. It could be simply that the compression crowned board 
> is doing what they all seem to do eventually. The timing stinks though 
> since this happened within about 8 months of them making the purchase.

You havnet said anything about whether the piano functions well or 
not... how does it sound ?  how does it play ? Has it actually started 
developing ridges yet ?  We've all seen plenty of instances with some 
ridges evident in panels without that really wrecking the sound or 
performance of the instrument. 

Unless you have a real problem there... take control... tell your 
customer that to prevent any such problem he needs to control the pianos 
environment and that to do so he needs accurate information. 

>
> Best,
> Greg


Cheers

RicB