Baldwin Epoxy adherence ?

[Delwin D Fandrich]

----- Original Message -----
From: "Isaac sur Noos" <oleg-i@noos.fr>
To: "Pianotech" <pianotech@ptg.org>
Sent: July 25, 2003 11:57 PM
Subject: RE: Baldwin Epoxy adherence ?


> Joe,
>
> I of course agree with the first part of the sentence, epoxy fills,
> but when it comes to adhesion, the wetting capacities of epoxy looks
> poor to me, so the bond is more mechanical than structural.
>
> I like to hear what others have to say about those resins as glue (I
> know there are some specific compound for epoxy glues)

Most of us who use epoxy regularly use products designed for wooden
boatbuilding. It is expressly designed to work well with wood. True, these
epoxies do not have as much bonding power as other woodworking adhesives
when both are used under ideal conditions. However, in repairs such as
loose bridges it is often impossible to get a perfect wood-to-wood fit
without completely disassembling the piano. This means that their is going
to be a slight gap between the two adherends. There is no other commonly
available woodworking adhesive that has good gap-filling characteristics
besides epoxy.

It is our practice to use traditional woodworking adhesives whenever
possible and/or practical. In those situations where a gap may exist
between two components we use epoxy (either straight or, most often, with a
wood flour filler).


>
> Did some meet failed epoxy glue joints in this domain ? gluing back
> post and wrest plank ?

We do use epoxy while gluing in the belly braces we add to grand pianos. We
also use a filled epoxy to accomplish the final bedding on pinblocks and,
sometimes, while gluing them into the rim. I've not known of either to
fail. None of these are applications in which the joint will be under high
stress loads. One thing to keep in mind--epoxy does exhibit a fairly high
amount of creep under long-term stress.

Our shop has seen a broad assortment of loose bellybraces that have been
glued by other means and other adhesives, however. Epoxy, because it
penetrates endgrain well and because it is a good gap-filler is the only
adhesive that makes a reasonably good butt joint bond.


>
> One thing I experimented myself with epoxies is the immediate (one
> good exposure only) rise of an hyper sensibilization, and now,
> whenever I file, sand or work on epoxy that is may be not totally
> cured, my hands are itching and get red (I feel they are ready to grow
> if I insist).
>
> Wear mask and gloves (I had mask only), it is very annoying as the
> same reaction occur with polyester repairs also.

Yes. Just like the directions and warning labels all say--protect your
skin. At the least use one of the readilly available protective skin
creams.

Different people react differently to these products. Some can get by with
using them for years with no problems at all. Others, after becoming
sensitized, can not be in the same room with uncured epoxy resins.

So far, I've been lucky but this is one of the biggest drawbacks to using
epoxy. That, and it's very messy stuff to work with.

Del