This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Hi Terry, Very interesting. I have to hand it to you, you really do get into things. Best regards, ----- Original Message ----- From: Farrell To: pianotech@ptg.org Sent: Saturday, March 29, 2003 11:31 PM Subject: Soundboard Torture This is what your soundboard wants to do when exposed to high humidity. Below is a photo of my mechanical moisture content (MC) meter. The wooden part is a 4-foot long by 4-inch wide chunk of soundboard panel. The panel is about 3/8 inch thick and has two ribs on the back (bottom in this photo) that are about 3/8-inch thick by 3/4-inch wide. The ribs were glued on when the panel and ribs were flat and at about 4% or 5% MC. The meter has been in an 85% to 89% RH environment for three days now. It seems to have nearly stabilized. I did not measure the crown, but as you can see it is somewhere around 6 to 8 inches. Picture removed for reply Soundboard panels in pianos exposed to high humidity are trying to do what you see above. The stiff ribs and string downbearing pressure keep it from actually developing 8 inches of crown. And instead of being able to expand and produce this kind of crown, the soundboard simply crushes. No wonder soundboard panels develop pressure ridges and then cracks when they dry back down! The scale on the left goes from about 5.5% MC to about 8.5% MC. The panel should be in the range of 18% MC in this photo. Fun stuff! Terry Farrell ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/a9/35/a9/7e/attachment.htm ---------------------- multipart/alternative attachment--
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