[CAUT] pre-stretching new string?

[David Love]

There are two separate issues both influencing string length, ultimately:
1) a change in the moisture content of the wood in the piano which
influences the speaking length due to expansion and contraction 2) a change
in temperature which changes the length of the string directly.  

The issue is how a change in speaking length affects a change in pitch and
which factors contribute to the degree to which there is a change.

It's not that difficult, if you want to take the time, to algebraically
alter the formula for string tension, diameter, length and pitch to isolate
pitch as the dependent variable.  Set up two notes of equal pitch but
different tensions/BPP etc.  Notice what must be different in order to
achieve equal pitch.  Find out what happens to pitch with an equal change in
speaking length of each.  

David Love
davidlovepianos at comcast.net 
www.davidlovepianos.com