Rob, Greg, and List: I have not made a statistically valid, replicated study, so this is anecdotal only. Before moving to near-coastal BC, I lived in Southern Ontario. RH in summer is *often* above 80%. Indoors, in winter, it is often below 20%, because it is being raised 40 degrees C or so (about 85 degrees F.) from the outside temperature. In older upright pianos in particular (Heintzman, Bell, Martin-Orme, Henry Herbert, Gourlay--1910 to 1935 vintage (maybe because of fewer/thicker pinblock laminations?) there is often a discernible difference between mid-summer and mid-winter pin torque. In several cases where the instruments were in otherwise tolerable mechanical condition, but the pin torque was marginal in winter, there was enough of an improvement with installation of a D-C system to put off repinning, at least for a few years. Rob--I'm a prairie boy, and I know about the climate in Edmonton. I am not too surprised that you would not see such a difference there. I think that the *amplitude* of humidity fluctuations contributes to loose pins more than absolute dryness does. I think the illustration in the new D-C promo video is pretty good. Swelling of the pinblock by high summer humidity could conceivably cause some crushing of the wood cells at the pin/wood interface, and this would leave the pins that much looser at the dry end of the cycle. Tim Keenan Noteworthy Piano Service Terrace, B.C.
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