Pitch Drop

[drose@microcity.com]

Has anyone any idea about how much pitch drop is apportioned between
humidity drop and stretching of strings?

An example a mason & risch 42" upright (think Aeolian) pitch raised 25
to 50 cents @ 67 degrees f. and 60% humidity. Six months later requiring
second pitch raise of 12 to 25 cents @ 68 degrees f. and 30% humidity.

I, of course, recommend humidity control to all my clients. But I would
still like to see other people's opinions and any study results.

p.s. Torque on tuning pins on the above piano 80 inch/lbs. before pitch
drop.