Most of the 1920's player pianos that I have worked on have severe moth
damage to the felt under the keyboard.  I often take "before and after"
photos to show my customers the improvements I have done to their piano
itself which is not evident with the keyboard in place.

I have purchased felts for the past 40 years from Schaff Piano Supply
Co.  They used to advertise that their felt was moth proof or moth
proofed and I have been telling my customers that modern materials are
treated to prevent moth damage.   I now note that their current catalog
no longer lists their felts as "moth proof" nor do they stock a product
to deal with moth problems.

I just visited a 1920 H. P. Haines player piano in which I replaced
all felts under the keyboard in 2007.  After only eight years, all of
the felts under the keyboard have evidence of some moth damage.  I now
wonder if I should have been placing small bags of moth balls or moth
crystals under my restored keyboards to prevent future moth damage.

I'm just curious what other restorers have done to prevent future moth
problems.  Is there an effective modern chemical treatment that should
be used on the felt materials to moth proof it ourselves?

Larry Schuette - The Player Piano Man
Raymond, Nebraska