Crystallizing of the old Shell Epon 862 followed the same
pattern. It would turn milky and a bit slushly if allowed to cool too far
for too long. Put it into a container and heat for a couple of hours (I
think 140F was the magic number here as well) and it would come good and tests
showed it to be OK. However, if it crystallized in the Sticky Stuff
Dispenser, the presence of residual crystals in the pump would stimulate low
temperature re-crystallization. So you need to heat the whole pump, or
clean it thoroughly before returning the reclaimed resin to the pump.
Resins are generally very stable and can be reclaimed.
Hardener systems are different. Many crystallize due
to presence of water vapour or carbon dioxide, and when they go, they are gone.
Into the circular file, order more.
Fred Moreno
-----Original
Message-----
From: Chuck Jensen
[mailto:cjensen@dts9000.com]
Sent: Friday,
10 April 2009 1:01
AM
To: lml@lancaironline.net
Subject: RE: [LML] Jefco
"The jefco resin in the 5
gallon drums if left on a concrete floor or
steel floor the resin can pull the cold up into the container and ruin
the resin. Make sure the resin is stored properly for long use."
Not to put too fine a point on it,
but 'cold' does not exist. Cold is simply the absence of heat, so the
heat in the Jefco may conduct down to the cold floor, but such conduction is
not a major factor in a media freezing. The heat radiation and conduction
to the surrounding air is a much bigger loss. Some concrete slabs, in
contact with the ground, may actually stay warmer than the air and, ever so
slightly, protect the Jefco from freezing.
Next, it should not be assumed that,
because the Jefco got cold and crystallized, that it is ruined. We use
polymer by the ton, literally, and if our polymer freezes and crystallizes, we
must rewarm the polymer to about 140F to dissolve the crystals.
Thereafter, the efficacy of the polymer is fully restored.
While this observation is pertinent
to an epoxy and styrene system that we use for a non-aviation purpose, it's
important to understand that such experience is fact specific; in this case,
product specific. I defer to the manufacturer of Jefco as to what their
recommendation is for their products. Out of an abundance of
caution, they may say not to use it for structural components, but I doubt
there is any problem with non-structural components.
You can confirm the viability of the
components if you do a PCP (process control program) bench sample to confirm
that the components cure to a rock hard product when applied to a test
strip.
-----Original Message-----
From: Lancair Mailing List
[mailto:lml@lancaironline.net]On Behalf Of marv@lancair.net
Sent: Wednesday,
April 08, 2009 8:06 PM
To: lml@lancaironline.net
Subject: [LML] Jefco
Posted for "Justin
Hawkins" <JustinH@lancair.com>:
All Lancair customers the build shop did a test on the Jefco resin, if
it gets close to freezing even for only a matter of minutes the resin
can crystallize and its properties ruined. So if that happens clean the
pump replace the resin.
The jefco resin in the 5 gallon drums if left on a concrete floor or
steel floor the resin can pull the cold up into the container and ruin
the resin. Make sure the resin is stored properly for long use.
Justin Hawkins
Lancair Airframe & Technical Support
Lancair Int. Inc.
250 SE Timber AVE
Redmond, OR 97756
justinh@lancair.com <mailto:justinh@lancair.com>
541-923-2244 ext 121
--
For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html