----- Original Message ----- From: "Jon Page" <jonpage@mediaone.net> To: <pianotech@ptg.org> Sent: January 04, 2001 9:23 PM Subject: Re: Was it something I said? Jon, On epoxying soundboard cracks, you said... > So far, I prefer to flip the piano upside-down and mask the 'topside' board > surface. > This way, any shrinkage of the curing epoxy will be on the bottom of the board. > ----------------------------------------------------------- If this is reasonably good epoxy, and I'm assuming it is, then there will be virtually no shrinkage. Epoxy is about the only adhesive that cures entirely by chemical reaction and not by solvent evaporation -- the reason for adhesive shrinkage. If an epoxy shrinks during cure it is a sign that it has been thinned by the addition of solvents which is generally not a good thing. Very thin epoxies typically take quite a while to cure enough to halt this absorption process. With the water-consistency epoxy we use it typically takes four or five hours. What is probably happening is that the wood is continuing to absorb epoxy for quite some time before the material becomes so thick that this is no longer possible -- which is a good thing. Del
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