We use commercial Super Glue ["CA glue"] in our shop for touching up
cracks in guitar tops.  This method I learned from friends at several
guitar manufacturing plants.

I would never use it to seal a valve seat in a player piano.  Use
shellac, just like the old timers have used for years.  Old shellac
dries very slowly.

The only place I would use Super Glue in a piano would be in a stripped
screw hole.  We have used Super Glue in old pin blocks when restringing
pianos and it seems to hold up well.  We coat the hole with Super Glue
and then ream the hole with the proper size reamer.

Don Teach - Shreveport Music Co.
Shreveport, Louisiana