Baldwin buckskin

[Kristinn Leifsson]

Hi people,

I´ve been noticing that on a lot of Baldwins I´ve seen there is hard 
buckskin, both on the hammer butt and on the back-catch.
What causes this?
These are pianos from around the 70's, I think.


Anything that I can do except replace them?

Best regards,

Kristinn