Hi Ed, And what might that literature be? A Journal article written years ago by the late Willis Snyder (and referred to many times in classes he presented) dealt with verdigris. He had several electron microscope photographs that made his point (that verdgris'd felt and even associated wood are completely compromised) rather well. Otherwise . . . I can't recall any literature, aside from assertions (pro & con) about dry cleaning fluid, ProTek CPL, zappers, etc. And elevated "common knowledge" on the lists, whispers passed down from master craftsmen, etc. Bibliography, please! Meanwhile the non-authoritative Wikipedia has an entry dealing with non-piano verdigris which may be of interest. To quote a couple passages: "Verdigris is the common name for a green pigment obtained through the application of acetic acid to copper plates[1] or the natural patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea will be a basic copper chloride.[2] If acetic acid is present at the time of weathering, it may consist of copper(II) acetate." "It was originally made by hanging copper plates over hot vinegar in a sealed pot until a green crust formed on the copper. Another method of obtaining verdigris pigment, used in the Middle Ages, was to attach copper strips to a wooden block with acetic acid, then bury the sealed block in dung. A few weeks later the pot was dug up and the verdigris scraped off. One method used in the early nineteenth century had to do with reacting copper sulfate solution with solutions of lead, barium, or calcium acetate. Their sulfates are insoluble, forming precipitates and leaving the copper acetate in solution." And other cool information (thank you, Jimmy Wales!). So -- in some recognized situations -- water appears to be related to the production of verdigris. Patrick Draine Nitpicker On Jan 2, 2011, at 8:44 PM, Ed Sutton wrote: > I strongly agree with Paul Revenko-Jones. > Nothing in the literature supports the claim that humidity causes verdigris in piano actions. > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20110103/eed4ef9b/attachment.htm>
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