ANY rust will be converted to a black polymer including rusted string coils. I consider that a plus as it stops the rust on the coils. If there are new strings on rusty pins as a replaced string the shiny steel will not turn black nor the pressure bar if it is shiny metal and/or nickel plated. Brass and aluminum are not affected either. No problem with felt either. The nice thing about the Klean-strip and Permatex rust converters in the spray can is that overspray on other surfaces does not show at all. Don't use Rustoleum brand and some others that have some black pigment that will show. Putting the Rustoleum brand on by hand with a brush can be done but it takes a lot of time. That is why I like the spray. The Cable piano in the previously attached photos was sprayed with no affect on the pressure bar or plate. I did shield some of the pins for the comparison so you could see the before and after. Doug Gregg Classic Piano Doc Southold,NY
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