False Beats in high treble after stringing

[Robin Hufford]

I have forgotten - endothermic or exothermic?  Ah, I believe it is the latter.
The heat produced by the curing process is evolved by the reaction itself which
is probably a polymerization process and, as such, the liberated heat itself is
secondary.   That is to say,  it is a consequence of the reaction itself and
does not, per se, drive it.  Although, should  the material be subjected to an
external source of heat it will gain energy and the reaction itself be
accelerated as a result.  This is distinct from an endothermic reaction - one
that absorbs heat as the reaction proceeds.  I think, in either case, the
reactions themselves require time to some degree or the other and this explains
why it doesm't  instantly harden up as you say.
Regards, Robin Hufford

Greg Newell wrote:

> Ron,
>
> So, what I'm understanding is that you have a drastically shorter working
> time. O.K. I can live with that. I was just having trouble understanding
> how it didn't instantly harden up instead of wicking into the hole as
> desired. Thanks!
>
> Greg
>
> At 09:56 PM 6/10/2003, you wrote:
>
> >>O.K. this is something I've been confused about for some time now. I
> >>thought that the chemical reaction between the two components of epoxy
> >>were what caused heat and therefore the curing or hardening process. If
> >>you heat with a hair drier or heat gun how does the epoxy thin and not
> >>harden? I believe you, I just don't know how this is possible. Is there a
> >>different way to mix the epoxy or a different product to buy?
> >>
> >>Greg
> >
> >Heat thins the epoxy momentarily, but accelerates the cure rate too, so
> >the net effect is better penetration but a shorter working time. It can
> >get touchy, depending on your epoxy and mix proportions when you find that
> >as the stuff cools from your heat application, it goes from the viscosity
> >of water to that of tar - or stone. Best to experiment some with an
> >unfamiliar product to get acquainted with it's characteristics before
> >committing in a piano. If you ever need to know anything about epoxy, ask
> >Terry.
> >
> >Ron N
> >
> >_______________________________________________
> >pianotech list info: https://www.moypiano.com/resources/#archives
> >
>
> Greg Newell
> Greg's piano Forté
> mailto:gnewell@ameritech.net
>
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