Formaldehyde glue/2

[Delwin D Fandrich]

----- Original Message -----
From: "Delwin D Fandrich" <pianobuilders@olynet.com>
To: <pianotech@ptg.org>
Sent: October 30, 2000 9:02 AM
Subject: Re: Formaldehyde glue


>
> ----- Original Message -----
> From: <Wimblees@AOL.COM>
> To: <pianotech@ptg.org>
> Sent: October 29, 2000 7:39 PM
> Subject: Re: Formaldehyde glue
>
>
> > In a message dated 10/29/00 8:15:04 PM Central Standard Time,
> > zahrprice@earthlink.net writes:
> >
> > << My problem is that old glue.  I know there is no way I could clean
all,
> >  or even most, of it out of a gap that's barely 1/4 inch wide.  And the
> >  granule are so hard I'm sure they would prevent the two surfaces from
> >  being clamped together effectively.  Does anyone know of a way to
soften
> >  or dissolve formaldehyde glue?  Can it be "reactivated"?  If it were
> >  softened or partly liquefied, would it interfere chemically with other
> >  glue, like Titebond?  Based on what little I know about formaldehyde
> >  glue, I'm not sure I want to use it in my shop.

--------------------------------------

My answer could have been a bit more complete...

Phenol-formaldehyde adhesives are not likely to be used in the average piano
shop.  It is a production adhesive designed for high-speed assembly.  It
required relatively high temperatures to cure, hence the RF heating ovens.

I'm guessing, but I suspect that there might have been something wrong with
the original assembly process in this case.  These adhesives require a very
thin glue line.  If there is that much crystallized adhesive floating around
it is quite possible that something was preventing the wood parts from
mating closely and the glue line was excessively thick.  With these
adhesives bond strength decreases rapidly with thicker glue lines.

As I said earlier, no, these adhesives cannot be 're-activated.'  They are
water proof.  There may well be some chemicals somewhere that will break
them down, but I don't know what they would be and I suspect you wouldn't
want them in your shop either.

If the crystal residue is loose in the gap, it would probably be a good idea
to clear out as much of it as possible before trying to bring the two
surfaces back together again.  Try compressed air.

There...I think that is all I wanted to add.

Del