ChrisRis@aol.com wrote: > > While we're on the subject, just what IS vertigris??? The story I personally > like best is that a drop of sperm whale oil was put on each bushing to > 'stabilize' it, and over time a fungus fed on the oil producing 'vertigris' > (which then isn't truly vertigris). I've graduated from the brass pin > corrosion theory, because the brass is plated and if you clean a vertigris > encrusted pin the plating is still shiny, covering the brass completely. I'm > ready for THE definitive answer to this question! > > Regards, > > Christopher OK, I guess everyone except Chris saw my post of about a month ago, but here it is again: Verdigris" is a Languedoc word (Provencal, spoken in southern France, is a modern descendant of Languedoc) which best translates as "grayish green." It is rust - specifically corroded copper, which is one of the metals in the alloy used for center pins - and can be caused by corrosive agents like sulfur or chlorine. Since rust is porous, it can absorb other substances like the lubricants used to treat (or mistreat) action centers, or whatever chemicals may remain or have been deliberately introduced into the bushing cloth. A chemical reaction can sometimes take place between these substances and the corrosive agents, the result of which is usually a thickening of the substances. Polymers are highly stable long-chain molecules which for all practical purposes will react with almost no chemical, and certainly not with anything encountered in action centers or anywhere else in the piano. Their only effect is to reduce the friction of whatever they coat. Protek CLP therefore makes the corrosion and whatever other gunk (an esoteric technical term) may be there slipperier than it would otherwise have been. Furthermore, the slipperiness is long term, because of the stability of the polymers. Hope it helps. Paul S. Larudee, RPT Richmond, CA
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