Compreg Panels (was Re: Piano Construction Origins)

[Phillip Ford]

On Sat, 23 Nov 2002 11:09:28 -0800 Delwin D Fandrich
<pianobuilders@olynet.com> wrote:

> The Compreg -- COMpressed, imPREGnated, wood
> fiber -- process was developed
> to replace brass and aluminum (both
> non-magnetic materials but prone to
> cracking and other catastrophic work related
> stresses) engine stringers for
> mine sweepers.
> 
> The process involved coating maple veneers with
> a (then recently developed)
> resorcinol resin adhesive and allowing it to
> dry. Resorcinol resins will dry
> without curing. The veneers were then placed in
> a heated press and taken up
> to (if memory serves) somewhere between 600 and
> 900 psi and something over
> 500º to 600º F. (Details are sketchy. It's been
> a 20 years since I read the
> research paper which might still be available
> from the USFPL-Madison.) The
> combination of pressure and heat would liquefy
> the resorcinol resin and
> force it into the wood fibers. (All of this was
> kept from burning by a
> nearly complete lack of oxygen.) It would also
> force a rapid cure to the
> resorcinol resin. The resulting
> fiber-reinforced plastic was both more dense
> that brass and much, much tougher.
> 
> The Baldwin pinblock making process is closely
> related to the Compreg
> process with somewhat lower pressures and
> temperatures resulting in a
> slightly less dense fiber-reinforced plastic.
> 
> Regards,
> 
> Del
> 

Was this stuff ever tried for rims?

Phil F



Phillip Ford
Piano Service & Restoration
1777 Yosemite Ave - 215
San Francisco, CA  94124