I had always thought that lost motion that can develop in a low-humidity environment (i.e. the winter months here in Chicago) was due to the wood action parts drying out and shrinking. I guess that's an incorrect assumption. I just came across a Kawai vertical that had quite alot of lost motion, but all the action parts were plastic, except the key itself. Plastic wippen, plastic jack, and plastic hammer butt. I didn't think plastic is affected by humidity. My guess is that the felt and leather (on the wippen and hammer butt) must have shrunk due to low humidity creating the lost motion. Or is there some other reason that pianos develop lost motion in low humidity? This piano has not been played much since I saw it last year, so I don't think it's due to wear. Tom Sivak
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