Felt Warning

[Ken Jankura]

     List, I recently serviced a nice Yamaha C7 where someone had muted off
an offending section of front duplex. As I was doing some regulation,
voicing, etc., I took it out to see if it was necessary. The entire area
where the felt was was crusty with rust. The felt looked like what is
commonly referred to as nameboard felt. I don't know what percentage
synthetic fiber is in that stuff, but it was enough to hold in the
moisture, and do some damage. The piano is only 12 years old. It may be
common knowledge, but please make sure to use only 100% wool felt against
strings. Is there any way to tell when felts are part synthetic. Aside from
seeing if they melt when you burn 'em :-)
     Ken Jankura