Hey LML gang,
Gary Hunter,
a friend and epoxy expert you may have seen before briefing at Oshkosh, sent this reply after we forwarded
him part of the LML discussion on Jeffco resin crystallization. I think
he tried to send it to the LML -- but, it probably didn't make it through since
I don't believe he's registered... Here is Gary’s message below.
BTW, Rhino Linings bought Jeffco. The same
products are still available, just new company name.
Valin Thorn
Legacy
Houston,
TX USA
-----Original
Message-----
From:
gary hunter [mailto:lucyliu22@mac.com]
Sent:
Friday, April 10, 2009 11:46 AM
Subject:
Re: [LML] Re: Jefco
WOE
JUST A MINUTE FOLKS....
If
we are talking about Jeffco laminating resins ... Listen up.
Just
because the resin is crystallized, it does not mean it has gone bad. It
is
perfectly normal for the resin to crystallize. Epoxy resins at ambient
temperature
is a "super cooled" liquid. What that means is, that below its
melting
point... ~ 130F...the product remains a liquid. A dust partical, a
seed
crystal and cool temperatures (like the floor of your garage) will
accelerate
crystal formation. The most pure resins, crystalize fastest.
Using
the material in the crystallized state is a no no. If the resins is
hazy..that
is an indication it has begun to crystallize.
HOWEVER,
the resin can be "Reconstituted" by heating it above the melting
point
of the crystals. Once the product becomes clear, free of haze and
crystal
material, it can be cooled back down the room temperature. The
resin
is good as new and has not suffered any degradation what so ever.
The
important part is to Reconstitute the entire contents of the container.
The
epoxy resin formulations we use can be mixtures of different types of
resins
to get the best overall properties. Some of these different types of
resins,
are not super cooled liquids and do not crystallize. So the resin
portion
that crystallizes is more dense, and settles to the bottom of the
container.
If you pour off the liquid part sitting on top of the
crystallized
part, it will not be the same composition of the original
mixture.
So, if you find a container of resin that is not clear all the way
to
the bottom. Heat the whole container to melt all the crystals. Stir
or
shake
it little to mix things back up, then you can pour off what you need.
The
safest way to heat the resin is the seal the container tightly, and
place
it into a bucket of hot tap water Keep refreshing the hot tap water
until
the resin is sufficient hot to melt the crystals.
If it
is a 5 gallon can, I highly recommend you invest in a silicone heating
strap
from McMaster Carr or some outfit like that. Some of you innovative
types
may find a cheaper way.
It
is not necessary, but some builders find it handy to keep their resin in
a
hot box...like an Igloo cooler with a 40W light bulb in it. This keeps the
resin
nice and warm and prevents crystal formation. The warm resin wets out
the
fabric faster, but it will shorten the working time.
Storing
you resin on the concrete floor will speed up the crystal formation
process.
Place a couple 2X4's between the container and the floor.
Some
of you may know me, Jeff Bassman of Jeffco does. He was one of my
customers
in the past. I am an epoxy resin chemist of 30+ years, currently
working
for Dow Chemical Company formulating resins systems for various
composite
applications.
If
any of you have any questions on epoxies for homebuilders... Feel free to
email
me. I provide the same type help for the various canard builders too.
Gary Hunter
Gary Hunter
Composites
117 Mesquite St.
Lake Jackson, TX 77566
281-433-8478
Lucyliu22@mac.com
___________________________________________________________
On
Apr 9, 2009, at 6:52 AM, vonjet@gmail.com wrote:
And
for those of us in the past 10 years who built planes with
Jeffco
that was stored cold or on the floor. Well, good luck and
hope
your plane stays together. Wonderful news to learn of now. Would
have been nice to know this
yesteryear.
______________________________________________________________
------Original
Message------
From:
marv@lancair.net
Sender:
Lancair Mailing List
To:
lml@lancaironline.net
ReplyTo:
Lancair Mailing List
Subject:
[LML] Jefco
Sent:
Apr 8, 2009 5:06 PM
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