Epoxy

[Farrell]

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Thanks Carl. You may well be right about higher temp curing not =
affecting the epoxy strength. I read all through the West System web =
site and could find no reference to it. They did identify the weakness =
caused by solvent thinning the epoxy resin, but apparently heat will not =
compromise it.

Terry Farrell
 =20
  ----- Original Message -----=20
  From: Carl Meyer=20
  To: pianotech@ptg.org=20
  Sent: Sunday, January 06, 2002 2:15 PM
  Subject: Re: Epoxy


  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

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