Today I checked the humidity on a client...61F/42%...in a church...piano heaven, so to speak...'-] David Ilvedson, RPT Pacifica, CA 94044 Original message From: "Jim Busby" To: caut at ptg.org Received: 12/9/2008 4:14:32 PM 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut_ptg.org/attachments/20081209/0fe34b91/attachment-0001.html>
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