[CAUT] Vertigris on Action Rail

[Ed Sutton]

Good comments, Brother Ed! 

I was unsure about the possibility of lanolin, not sure how much the cloth has been cleaned. Historically, mild acids were also used to produce verdigris pigments. Apparently copper can react with just about anything. 

I hesitate to go further because of my ignorance of chemistry, but my metallurgy book mentions that tiny amounts of "deoxidizers" such as phosphorus  are commonly alloyed with copper to prevent weakening by scattered oxidation. This might account for the relatively slight oxidatin we see on bass strings.

In an increasingly digital/virtual world, I find great solace in our grunt relationships with actual stuff!

Ed S.
  ----- Original Message ----- 
  From: Ed Foote 
  To: ed440 at mindspring.com ; caut at ptg.org 
  Sent: Monday, August 02, 2010 7:41 AM
  Subject: Re: [CAUT] Vertigris on Action Rail


  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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