Bill Ballard wrote: > Thanks, John. You've got me started on my own homework assignment. When > you say, "narrow these figures about 10%", it seems you mean 60% RH - > 10% RH, instead of 60% * .9. I need to adjust the figure for a board > ribbed @ 4.5%, on the assumption that was the operating EMC (as Del > would assume). 20% to 50% RH is a rough estimate for a safe environment for a board ribbed at 4.5%. It is hard to know for sure because the amount of panel compression depends on various factors and is a little hard to figure out. > That EMC will determine what the ceiling for ambient RH the piano owner > must enforce. Regardless, the piano is now dependent on climate control > to stave off premature splitting. Ironic, considering the dealer's > attitude towards D-Cs (he hadn't heard of the Smart Bars) and the > regional rep (he stated that Steinway discouraged their use), and > Petroff's official position on climate control and D-Cs. Climate control is important but what about getting a finish on the board that has a reasonable chance of staving off temporary spikes in humidity? It is a amazing how fast an unfinished board will respond to changes in the RH. When it comes to protecting the wood from these spikes the main factor is the thickness of the finish not what type of finish. At least this is what I have read. Pigmented finishes like house paint work even better but it's too hard to create a convincing faux grain. I use varnish because I can get enough on in a reasonable time frame. Three or four brushed coats seems minimal to me. I wonder how many coats of lacquer it would take to get the same protection? John Hartman RPT John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] Rebuilding Steinway and Mason & Hamlin Grand Pianos Since 1979 Piano Technicians Journal Journal Illustrator/Contributing Editor [link redacted at request of site owner - Jul 25, 2015]
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