Thin Epoxy

[Kerry Cooper]

Del,

If this CPEST is flexible, wouldn't that detract from the vibration
transmitting characteristic required to produce a good clear sound?

Kerry Cooper
Australia
----- Original Message -----
From: "Delwin D Fandrich" <pianobuilders@olynet.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Thursday, February 27, 2003 4:49 PM
Subject: Re: Thin Epoxy


>
> ----- Original Message -----
> From: "Farrell" <mfarrel2@tampabay.rr.com>
> To: <pianotech@ptg.org>
> Sent: February 26, 2003 7:54 PM
> Subject: Thin Epoxy
>
>
> > I ran across this site and thought of Del and Ron N. and Ron O. They are
> out by Del. The topic of low viscosity epoxies has come up on the list
> often.
> >
> >   http://www.rotdoctor.com/products/product.html
> >
> > A couple very interesting products:
> >
> > -    CPEST (Clear Penetrating Epoxy Sealer)
> > -    Tropical Hardwood Epoxy AdhesiveT
> >
> > The sealer is said to be of diesel fuel viscosity and penetrates into
wood
> way more than other epoxies (laminating bridge caps - your soundboard
> coating thing). They also claim that WestSystem is petroleum based and
cures
> brittle (I certainly agree that it is brittle).They say their epoxy is
wood
> based and cures flexible. I'm not sure exactly how that might
benefit/effect
> our work on pianos, but there it is (in a bridge cap, I don't see where it
> would make much difference - brittle or flexible). The penetrating sealer
> really gets my interest. Hmmm. Maybe we can laminate a thin strip of
Kevlar
> into those bridge caps and use this penetrating sealer for the ultimate
> bridge cap - 'course it might be a bit of work to get a pin in it and to
> notch it.
> ------------------------------------------------------
>
>
> I am aware of this product, but have not used it. I've been just a bit
> apprehensive, mostly because I consider the advertising and promotion,
along
> with the so-called comparison tests, to be just a little bit misleading.
> Basically, CPEST is a solvent-thinned epoxy resin. The major difference
> between this and other standard structural epoxies is that CPEST is
supplied
> pre-thinned. In these 'tests' only its penetrating capability, not its
> structural strength, is being compared, yet the other standard,
> multi-purpose coating and penetrating epoxies have not been thinned to
> anywhere close to the viscosity of CPEST. I suspect that if the other
> epoxies had been thinned out with their appropriate solvents to the same
> viscosity as CPEST they would have penetrated much better than is
indicated
> in this test. They would also loose some of their structural strength, as
> does, I suspect, Dr Rot. But this characteristic is not tested. You may
> notice that CPEST is not really being marketed as a structural epoxy while
> the others are. In terms of flexibility, if structural epoxies such as
WEST
> System or System Three structural epoxies significantly they cure to a
> somewhat more flexible state as well.
>
> So, what have we? I suspect that CPEST is a basic structural epoxy thinned
> with whatever thinners are appropriate for the resin/hardener system and
> sold as a thin, penetrating epoxy sealer that is "strong." Before becoming
a
> believer I would like to read an independent analysis of the material.
>
> Besides, in the soundboard work I've been doing I don't want the kind of
> penetration being described by Dr Rot. These boards are not rotten, they
are
> structurally and stiffness impaired. I want all of the structural strength
> and stiffness I can get. O.K., within reason.
>
> Del
>
>