Charles: I have experienced the problem of a piano going out of tune after the case has been opened, particularly on uprights, but I have always attributed the drift to a change in temperature rather than humidity. This happens especially on a cold morning, or when the owner has just gotten home and turned up the heat in the house. I can feel the temperature of the plate, and it is usually pretty cold. I know then that the strings will be cold and will react quickly to the warmer air hitting them. Whenever possible I will do any necessary repairs first so as to let the strings warm up before I start tuning. The first time I noticed this phenomenon is when I was tuning at a house where the furnace repairman had just left. He had cranked the thermostat up to 90 to be sure it would come on, and then went off without turning it back down. Halfway through the tenor section the furnace came blasting on, working really well, and the temperature in the house shot up. Needless to say those first couple of octaves went haywire, and I had to wait for the house to cool back down and then started all over. This can also be a problem in a concert hall which hasn't been brought up to room temperature before I get there. I always ask that the hall be up to "performance" temperature, and they *usually* remember to do it. There have been occasions where I've had to go off and do another call to give the hall time to warm up. Other times I have just had to say "that's the best I can do under the circumstances". After all, its not my piano! :-) Patrick Poulson, RPT
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