[pianotech] Removing glue and felt residue

[John Delacour]

At 23:30 -0800 12/12/08, Denis Kelly wrote:

>I have a Baldwin Grand from the the 1920's in the shop for a 
>rebuild. Does anyone know what kind of glue was used for such things 
>as the back rail felt, dampers, and other felt to wood applications? 
>Hot hide glue? Also, what's the best method for removing the old 
>felt and glue residue. The last time IÊdid this with razor blades 
>and sandpaper it took forever.

For the dampers, get a tall pan full of hottish water.  Add a drop or 
two of detergent and hold the felt in the water until it has wicked 
up to the underfelt.  Then just leave the dampers on the rack until 
the felts will either just fall off or pull off with no effort.  You 
might need to wait an hour or four hours depending on the strength of 
the glue.  Provided the heads are of a wood that holds the polish, 
the black finish will not be affected at all.  I they are made of 
maple (which does not hold a polish well) then you must work more 
carefully to avoid the black finish flaking off.

In other cases just soak the felt, wait for the glue to soften and 
pull it off.  If glue still remains, brush on more water, let the 
glue soften and scrape off with a blunt chisel or a piece of 
hardwood.  You may need to do this several times, so it's best to 
have another job on the go at the same time to get on with while the 
water softens the glue.

There is no virtue, in my experience, in adding anything to the 
water.  Just plain water will do the job.

To get the surface perfectly free of glue, which is not usually 
necessary, wipe it with a rag dipped in hot water.

JD