Epoxy on soundboards

[David Love]

Here's my real question:  If you dry down the panel and wedge it up,
then epoxy it and let it cure while the board is still in a dry state
and then allow it to take on moisture, will the panel crown a bit as it
takes on moisture? 

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Ron Nossaman
Sent: Tuesday, October 19, 2004 9:31 AM
To: Pianotech
Subject: Re: Epoxy on soundboards


>Those of you who do the epoxy coating on soundboards to try and recoup
>stiffness.  I can't locate the article that appeared in the journal.
>After wedging the board up, was it necessary or desirable to dry the
>panel down before applying the epoxy coating?
>
>David Love


Well, I have done the epoxy thing once. Do I qualify? I'm not altogether

sure if it needs dried down or not. This procedure works by making the
top 
surface of the panel less compressible, and the bending strength of a
beam 
(which this essentially is) is determined more by the compression 
resistance of the top than the tensile strength of the bottom (lower 
surface of the ribs), as long as the tensile stress is lower than the
limit 
the material will take. I would think It would  help to at least
pre-heat 
the panel (moderately), which drives out some moisture and a lot of 
expanding gasses, so the epoxy would be sucked deeper into the wood as
it 
cools and the gasses remaining inside cooled and shrunk. Whatever it
takes 
to get a good compression resistant top surface layer in the panel.

Ron N

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