Verdigris (Was Re: further clarification on query)

[Tim Keenan & Rebecca Counts]

List--

I should go and look at the archives, but my resources describe verdigris 
as principally copper sulfate, with minor components of other salts. The 
reaction happens everywhere copper is exposed to air containing sulfur 
dioxide (SO2)[everywhere on Earth, to a greater or lesser degree, but 
more near coal-burning power plants and active volcanoes] , but will 
proceed faster in humid air where SO2 becomes H2SO3 (sulfurous acid) in 
aerosol form.  It also forms as a result of contact with 
sulfur-containing acids on skin.  It cannot form if the copper doesn't 
come in contact with an acidic sulfur compound.

It occurs to me that prophylactic use of Protek or a similar product 
which leaves a PTFE film a couple of molecules thick on the copper 
plating of the pins ought to go a long way to preventing the accumulation 
of verdigris in the first place. If pins were "Protekted" when new, and 
occasionally thereafter, perhaps the problem could be greatly reduced.

I also notice that it doesn't seem to be directly related to age--perhaps 
some bushing cloths use sulfuric acid as a mordant in the dyeing process 
and it isn't always entirely washed out? I've seen pianos of virtually 
identical ages but different makes (circa 1905) in a church in Hamilton, 
Ontario (major steel manufacturing centre with coke ovens and stuff--lots 
of SO2) where one piano had no problem and the other was quite gunked up.

Whaddya think?

Tim Keenan
Noteworthy Piano Service
Terrace, B.C.