CA gluing Grand Pin blocks....My take on it/ Richard Brekne

[Isaac OLEG]

Thanks, a lot of good news.

I just downloaded "the Epoxy book" from System Three site,
http://www.systemthree.com/index.html  and indeed that is clearly
mentioned that the principal enemy if not the only one is UV.

Was not aware of that, but indeed I did not use Polyester but real
(expensive !) epoxy for stratification work.

This quality is very thin, so it is not building a lot of material,
and it goes deep in the porous material. Beside, it takes 72 hrs or
more to became hard, and it is easy to wash the extra. It may be the
same kind than their "Clear coat" quality may be.

Sure the pins seems to hold very well with this method.

If it remains as that after that it will be nice.

Regards.

Isaac OLEG

gone soon for a time !



> -----Message d'origine-----
> De : owner-pianotech@ptg.org
> [mailto:owner-pianotech@ptg.org]De la part
> de Delwin D Fandrich
> Envoyé : mercredi 31 juillet 2002 17:21
> À : pianotech@ptg.org
> Objet : Re: CA gluing Grand Pin blocks....My take on it/
> Richard Brekne
>
>
>
> ----- Original Message -----
> From: "Isaac OLEG" <oleg-i@wanadoo.fr>
> To: <pianotech@ptg.org>
> Sent: July 31, 2002 7:35 AM
> Subject: RE: CA gluing Grand Pin blocks....My take on it/
> Richard Brekne
>
>
> > Hi !
> > While using the thin epoxy coating holes method (and new
> bridge pins)
> > for pins that don't hold quite enough and little cracks
> on bridges, I
> > am not very sure of the holding in time of this material.
> >
> > Composite material mixing wood and epoxy will not age the same.
> > Epoxy used in gems (agates) to mask little defects (by
> inclusion under
> > high pressure) are first quality, and they show their
> presence in time
> > as they decompose.
>
> All epoxies--along with most other plastics--are
> susceptible to breakdown
> when exposed to ultraviolet light. They are quite stable
> when protected with
> either paints or clear finishes containing UV blockers.
> These UV blockers
> can take the form of pigments mixed into the material
> itself or can be
> included in a clear coating such as most any exterior-grade
> lacquer or
> varnish.
>
> Boats using epoxy extensively have survived quite nicely
> for 50+years so far
> and I assume--though I could be wrong--that epoxy
> technology has improved
> some during that time.
>
>
> >
> > Epoxy as the kind I use is the same as used for marine
> work for glass
> > fiber work, and don't have much strength by itself.
> > I believe that it will became brittle and probably dusty
> in awhile,
> > even if the sounding results are evident and the holding
> very good at
> > first.
>
> Most marine fiberglas work is done with polyesters--quite a
> different
> material from epoxy. You are correct, polyester has
> relatively little
> strength of its own. Only in matrix with the fiberglas
> cloth does the
> combination attain high strength. Many types of epoxy are
> used for boat
> building and boat repairs, but not often for fiberglas
> construction--it's
> too expensive even though its strength characteristics are
> vastly superior.
> Epoxy is quite a different material from polyester.
>
> But, as I said, it must be protected from UV light. In the
> case of bridge
> repairs, with the epoxy down in a hole somewhere, no light
> of any kind can
> get to it and it will be very stable. Even using it as a soundboard
> coating--as described in my current Journal articles--it
> will be stable as
> long as it is coated with an exterior-grade lacquer or
> varnish containing UV
> blockers and as long as the piano is kept indoors and
> generally away from
> direct sunlight shining on the soundboard surface. And if
> the piano is kept
> outdoors--at least where I live--I'd be more worried about
> how the rain than
> I would the sun....
>
>
> >
> > Beside, the wood aging will probably be slower once
> coated, Epoxy is
> > certainly used in restoration of old wood for museum
> pieces, but then
> > they are suppose to stay in a stable H.R. environment (and not
> > submitted to vibration).
>
> Epoxies--unlike CA's--have good resistance vibration.
>
> Del
>
>
>