S&S green goop

[A440A@AOL.COM]

 Christopher writes: 

>Ah, very interesting, now we're getting somewhere.  But it begs the question
>>- what is it that turns the tallow green???

Greetings, 
    I had always assumed it was free copper, atmospherically available in a 
"metallic tube" environment.  Electrolysis will happen between virtually all 
dissimilar metals, and with a slightly acidic, tallow-soaked buffer between 
the pin and the air? There is even  a little organic material in there to 
host a reaction.  The felt itself may have had metallic content, depending on 
the water used,etc.   
    I wish Don Galt,  a very forward thinking editor, metallurgist, and 
wide-awake technician of the past had addressed this.  Any of you "journal 
hawks" know what he may have written on the subject?).  
    I do know that once it grows out of the pinning so that it will rub off 
on your hands,  nothing is going to keep that action free.  And when I can 
see hammershanks slowing and the felt with a little green, I tell a customer 
it is time to try Pro-Tek, and be ready to replace if it doesn't work.  It 
usually happens that they often feel their piano free for the first time in 
years, and later, as it begins to go downhill again,  their priorities and 
finances will have had time to adjust.  Make sure that 
shank-hammer-damper-replacement job is not bid too low to take a years worth 
of delay!   

      In my life's collection of centerpinscraps, there are several different 
kinds of verdigris.  My classics are the purple tinged ones from a turn of 
the century Knabe and a large layer of red ones from some unknown upright,  
an early career project that taught me how hard it is to get your money out 
of a completely repinned (center, tuning, and bridge!) upright.  
Regards, 
Ed Foote