[CAUT] Vertigris on Action Rail

[Ed Foote]

 Ed S writes; 


My metallurgy reference says that verdigris can form just by exposing pure copper to moist air. Brass is less reactive than copper.
 

     I agree, yet, I have seen many verdegris actions in pianos with fine bass strings, so I suspect that there is more chemistry involved than simple oxidation.  The strings are nearly pure copper, the brass of the action rails is tin/copper allow,( or is it zinc that is alloyed?).  In any case, the verdigris I see in action cloth, and on rails, is exactly the same color and feel as the verdigris that forms on the brass key frame plates where I have used pure lanolin for  lube.  (Why, you may ask, do I use lanolin for lube, at that place?  I have never found anything that lasted longer or worked better, and the small tin of it I inherited from an older tuner, years ago, is showing all the signs of outlasting me). 
    I think there is a slight amount of acid in the lanolin, and that is what reacts with brass. It might be present in all felt, or Steinway may have used some particular pin, or a combination of the two. It's presence under the flange cloth makes me think that the activator in this deal is some kind of treatment in the felt, ( and leather!  I see a lot of verdigris on the tops of pedal rods). 
Regards,



Ed Foote RPT
http://www.uk-piano.org/edfoote/index.html
















 
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