Thanks Alan. This is most excellent. Jim -----Original Message----- From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Alan McCoy Sent: Wednesday, December 10, 2008 10:16 AM To: College and University Technicians <caut at ptg.org> Subject: Re: [CAUT] RH? Please enlighten me. Here are an EMC table and excel EMC calculator attached. Maybe they'll get through the filters. Alan -- Alan McCoy, RPT Eastern Washington University amccoy at mail.ewu.edu 509-359-4627 509-999-9512 > From: Jim Busby <jim_busby at byu.edu> > Reply-To: "College and University Technicians <caut at ptg.org>" > <caut at ptg.org> > Date: Tue, 09 Dec 2008 17:14:32 -0700 > To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org> > Subject: Re: [CAUT] RH? Please enlighten me. > > Thanks Don, all. Very enlightening. > > Don, this paragraph from you helps me better understand the "why" of > cracked soundboards. We really have been lucky here at BYU to not have more problems. > > Jim > > From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of > Don Mannino > Sent: Tuesday, December 09, 2008 12:41 PM > To: caut at ptg.org > Subject: Re: [CAUT] RH? Please enlighten me. > > <<<My little quick rough guideline I try to give piano dealers and > schools for soundboard health is the following: if you hold a room at > 22ºc and 25%, the Spruce in the soundboard will be dried to about 5% > EMC (very roughly - it does vary by species and density). So when the > humidity goes below 20% at comfortable room temperatures, then the > soundboard is being dried down farther than the factory did > originally, and the chance of cracks opening up is very high. Some > soundboards can handle this better than others, but eventually they > will seek relief from the shrinkage and will need to crack.>>> > > Don >
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