Epoxy

[Carl Meyer]

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Terry, the specs for max service temp for epoxy vary from 150-400 =
degrees F on a typical brochure I have from Hysol.  I've never heard =
that high temps at curing (under the max working temp) would weaken the =
result, but I may be wrong.  Most mfg. give a recommendation, but I =
think they say room temp cure merely to say that it will indeed cure =
without heat.  Some won't.

I recall years ago I worked for a company that made voice coils for =
computer disc drives for IBM.  The adhesive used to coat the windings =
was a structural adhesive made by MMM.  The cure schedule specified by =
IBM was 1 hour at 130 F followed by 1 hour at 250 C followed by 1 hour =
at 350 C.  (that's 842 F).  The normally green epoxy turned brown.  I =
gleefully informed the IBM engineers that the heat was in excess of the =
operating temperature specified by MMM.  After much gnashing of teeth, =
fancy footwork and backtracking IBM changed its specs, and
we found it's not too hard to be green.

http://www.epotec.com   is the website.  Epotec301 has a  Shore D =
hardness of 81

I've just learned that clear coat has a viscosity of approx. 600 for the =
resin and about 200 for the hardener.  I'm not sure how the mix relates =
but it should be about 500 since the mix ratio is 2-1.

Happy gluing.

Carl Meyer  Assoc. PTG
Santa Clara, California
cmpiano@attbi.com=20


  ----- Original Message -----=20
  From: Farrell=20
  To: pianotech@ptg.org=20
  Sent: Sunday, January 06, 2002 8:03 AM
  Subject: Re: Epoxy


  Hi Carl. My info is that elevated curing temperatures can tend to =
weaken the cured epoxy. It would concern me to heat bridge pins. It may =
not be a valid concern as I'm sure the heat is dissipated rather =
quickly. I have always found West System to be thin enough to wick into =
all birdseye cracks around bridge pins - when the pin are removed. I'm =
sure it would be nice to have an even thinner epoxy - although, I wonder =
if it would be as convenient to apply - the thicker West System holds a =
nice drop on a wire or on the bridge pin base for application! What is =
the strength characteristics of the Epotec301? Is it as strong/hard as =
West System resin? Do you have a web site for Epotec301?

  Oh, and BTW: Just sent out an old Fisher upright with a completely =
rebuilt action and a VERY nicely leveled set of keys!

  Terry Farrell =20
    ----- Original Message -----=20
    From: Carl Meyer=20
    To: pianotech@ptg.org=20
    Sent: Saturday, January 05, 2002 7:44 PM
    Subject: Re: Epoxy


    NSIP

    Epotec301 is expensive since it is optical grade.  I'm waiting for a =
spec sheet for clear coat, but I think it is similar to liquid wood.

    There may be other qualities of epoxy that will enhance penetration, =
but I would think viscosity would be the primary one.
    Warming the pinblock, bridge or other items helps a great deal.  A =
lot of spec sheets don't list viscosity, hardness and other parameters =
and there is no easy way to compare. =20

    Still learning all I can about epoxy!!

    Regards

    Carl Meyer  Assoc. PTG
    Santa Clara, California
    cmpiano@attbi.com=20

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