Spurlock Specialty Tools sells at set of three "squeegees" for reaching
through the strings of a grand piano to dust the soundboard.  I have
used the spring steel and cloth method that John Tuttle suggests, but
I find these tools work much better.  Priced at $20 when I bought them
several years ago.

  Spurlock Specialty Tools
  3574 Cantelow Road
  Vacaville, CA 95688
  tel/fax: 707-452-8564

Bill Maxim, RPT
Maxim Piano Service