I agree 100% with Don Teach and John Tuttle regarding hot hide glue.
I have worked on players that someone has used SOBO, Elmer's carpenter
glue, Elmer's Glueall to glue the rubber cloth on. When I get one of
those I add another $750 to the bill.
I have been using hot glue in my player and pump organ work since 1961
and have never had any problems with using hot hide glue. The only
thing is to make sure your glue is fresh as possible. I never add any
crystals to my pot. I let it get down to about a half-inch and then
I throw out the rest and make new. That way I almost always have fresh
glue. I hope the new technicians stay away from anything other than
hot hide glue. Those are my thoughts on the matter.
Baldwinsville, New York