Fw: Re:How to cook a piano

[BobDavis88@AOL.COM]

Sanra Cooper writes, via Pat Neely:

> One of my customers has an older Knabe grand that got cooked. The propane
>  > heat in her home went haywire and kept the house at an estimated 140
>  > degrees F for four days;

Hi Pat and Sandra,
There are specific areas I would worry about. First, remember that the 
nominal temperature of your glue pot is 140 degrees. If the temperature of 
the piano rises for a short time, the mass of the wood will act as an 
insulator and heat sink, but as time goes on, the temperature of the glue in 
the joint rises. How much? You can't know. Also, there are an awful lot of 
joints, some of them originally assembled under stress (think rim laminae, 
ribs, bridge to board, etc), and which are still under stress even after all 
these years, when the heat softens/weakens the glue. In most of these, the 
glue might set again without damage. However, even in joints that don't fly 
apart, one might be left with a weak joint which could fail at a later time.

Second, you don't know what internal stresses have been put on the wood in 
the soundboard, but I would consider them major.

Third, the resins in the finish suffered chemically, and the adhesion 
suffered mechanically from the wood movement under it.

So, I would consider the risk high enough that I wouldn't hesitate to 
recommend replacement to an insurance company. If it is not insured, I would 
try to minimize risk to the client in several ways. First, if I were going to 
try to salvage this piano, I wouldn't touch it for a year. Then I would look 
at the apparent condition of the soundboard and ribs, checking for popped 
glue joints all over, as well as listening to the sound. If the hammer felts 
stayed on the moldings, I would check the action for twisting of shanks now 
and after a couple of months. I would be very slow about putting money into 
the piano. A "complete restoration" would not address many structural joints, 
and would still leave the possibility of catastrophic failure, although this 
diminishes somewhat with time.

Too bad the temperature wasn't higher, and maybe it would have annealed the 
agraffes! (or would it?)

Good luck,
Bob Davis