<html><head><style type="text/css"></style></head><body><div style="font-family:arial, helvetica, sans-serif;font-size:12pt"><P>Hi Matthew: My guess is that there is some chemical in the damper felt that is interacting with the copper windings and leaving the black residue in the felt as well as on the string. The appropriate solution would seem to be replacement of the felts with material from a reliable source. i.e., not Kawai. Also clean the strings with naptha or some other light solvent as thoroughly as possible.</P> <P>Patrick </P></div></body></html>