From: Jim Hocut <jhocut@mindspring.com>
Subject: COZY: Stupid Epoxy Tricks
Date: Sun, 3 Oct 1999 00:44:43 -0400

Here's one I haven't seen reported yet.

Myself and a friend laid up the bottom spar cap on a wing a couple of 
days ago.  I'd done a careful job of masking the entire wing with 
plastic so as to avoid any epoxy blobs on bare foam, so it was no big 
deal to set squegees, brushes, and containers of epoxy on the wing as 
we worked.  After completing the layup it was getting late, so I 
chased my free help home to his wife and said I'd clean up the next 
day.  What I found the next night was that the epoxy left in the 
containers had exothermed, and had melted two  2 inch by 3 inch 
craters a half inch deep into the wing core.  It was no big deal to 
rout out the effected areas and micro in scraps of foam, but that 
added another half hour onto my wait 'till the wheels leave the 
ground.



Jim Hocut
jhocut@mindspring.com



Date: Sun, 03 Oct 1999 09:22:32 -0400
From: Jeff Russell <JRaero@gte.net>
Subject: Re: COZY: Stupid Epoxy Tricks

Jim Hocut wrote:
> 
> What I found the next night was that the epoxy left in the
> containers had exothermed, and had melted two  2 inch by 3 inch
> craters a half inch deep into the wing core.  It was no big deal to
> rout out the effected areas and micro in scraps of foam 

Did your spar caps do the samething?  What type epoxy? how much 
left in the cups? 
Thanks

-- 
Jeff Russell/AeroCad Inc.

From: Jim Hocut <jhocut@mindspring.com>
Subject: RE: COZY: Stupid Epoxy Tricks
Date: Sun, 3 Oct 1999 09:45:08 -0400

 
> Did your spar caps do the samething?  

Nope, spar cap looks real good.


>What type epoxy? 

MGS 285, mixed about 50/50 fast and slow.  Temperature was 78 deg F.
 
> how much 
> left in the cups? 

Somewhere over an inch standing in the bottom.



Jim Hocut
jhocut@mindspring.com



Date: Sun, 3 Oct 1999 10:18:47 -0400
From: Bill Theeringer <Composite_Aircraft_Accessories@compuserve.com>
Subject: COZY: Stupid epoxy tricks


During the construction phase I had the fuselage up side down and was
installing the landing brake.  I left the overhead heat lamp shining down
on the project from about 4 feet away and called it a nite.  It was cold in
the garage that evening.  Cats do migrate to warm spots, and it was a mess.
 The Siamese cats hair eventually grew back but it never did like me much
after that.

Bill T

Date: Wed, 6 Oct 1999 23:37:58 -0400
Subject: COZY: Cozy:  Epoxy mixing
From: Dana Hill <dhill36@juno.com>

	I recently purchased a small mixer, designed for paints, and I would
like to try to use it for mixing epoxy.  My problem is to use it with my
drill press I am going to have to slow down the rpm's-  way below the
slowest possible speed of the drill press.  
My question is, would anyone know what specific motor speed controller
(manufacturer/part #) I could purchase for this purpose?  The motor in
the drill press is 1/3 HP(small bench mounted).

Thanx,
Dana Hill
Cozy #676
Ch 7

Date: Thu, 07 Oct 1999 07:33:03 -0400
From: "L. Wayne Hicks" <lwhicks@erols.com>
Subject: Re: COZY: Cozy:  Epoxy mixing

Dana Hill wrote:
> 
>         I recently purchased a small mixer, designed for paints, and I would
> like to try to use it for mixing epoxy.  

-------> I understand your intent, but I'd have to add these deterrents:

1. You would still need to scrape the sides occasionally to ensure
thorough incorporation and mixing.

2. You only need a minute with a mixing stick anyway.

3. Too large a batch is a sure to exotherm anyway. 

4. Large batches are usually only needed when glassing the wings.  By
then, you'll have enough curious friends to help mix gobs of epoxy.

5. Extra cleanup.

Wayne Hicks

From: cdenk@ix.netcom.com
Date: Sat, 9 Oct 1999 18:23:01 -0500 (CDT)
Subject: Re: COZY: Peel Ply

On 10/08/99 22:54:52 you wrote:
planning to order the kits...epoxy 

Don't order too much epoxy, some of it has a shelf life, building time likely will be longer than you plan.

From: "wydo van de waerdt" <wydo.vandewaerdt@fae.storkgroup.com>
Subject: COZY: Pre-build: epoxy danger.
Date: Tue, 12 Oct 1999 10:57:41 +0200

Dear builders,

Is there still a possibility of getting an allergic reaction, when taking
all safety rules on epoxy in account ??


Regards,
Wydo van de Waerdt (NL)
#???? Pre-build

From: "Hunter, Gary GA SCC" <GH334766@MSXSCC.shell.com>
Subject: RE: COZY: Pre-build: epoxy danger.
Date: Tue, 12 Oct 1999 06:32:42 -0500

	Wydo van de Waerdt (NL) - asks.

> Is there still a possibility of getting an allergic reaction, when taking
> all safety rules on epoxy in account ??
> 
YES... but it is a very slight possibility compared to total negligence.
And, there is an EXTREMELY small percentage of people that are allergic to
epoxy resins AND / OR the curing agents much like some people are allergic
to certain medications like penicillin and bee stings.  

We tend to use the words "epoxy resins" all inclusive to mean the resin and
curing agent in a generic sense.   But, it in actuality the allergy may be
caused by one of several compounds in the resin "blend" OR the curing agent
"blend".   In cases like this, switching to an alternate brand of "epoxy
resin" may eliminate an allergic reaction one may be experiencing.
Sometimes, just switching the resin portion OR the curing agent portion will
do the trick.  For instance, many of you are using a blend of two MGS curing
agents (usually 50:50) to obtain the curing rate that you like.   It is
entirely possible that only one of those curing agents is the culprit.
Simply leaving it out would solve the problem.  Similarly, changing the
brand of curing agent may do the trick as well.   CAUTION - This kind of
action requires the help of the resin supplier or someone like myself to
recalculate mix ratios and to conduct an appropriate assessment of the
changes for suitability to the intended end-use.   It also entails a rather
lengthy trial and error testing sequence on the allergic subject (a.k.a.
guinea pig - you).

In conclusion, contracting and allergy to "epoxy resins" does not mean the
death of your project.    On the flip side, a casual approach to epoxy resin
sensitization could mean your death.  KEEP IT OFF OF YOU !!!

Kindest Regards,

Gary Hunter
Technical Service Representative
EPOXY RESINS TECHNICAL INQUIRY
SHELL CHEMICALS, USA

Toll Free in North America   - 800-832-3766
International                       - 281-544-6600
Facsimile                            - 281-544-6604
Email                                 - gahunter@shellus.com

> -----Original Message-----
> From:	wydo van de waerdt [SMTP:wydo.vandewaerdt@fae.storkgroup.com]
> Sent:	Tuesday, October 12, 1999 3:58 AM
> To:	cozy_builders@canard.com
> Subject:	COZY: Pre-build: epoxy danger.
> 
> Dear builders,
> 
> 
> Regards,
> Wydo van de Waerdt (NL)
> #???? Pre-build

From: MARC_ZEITLIN@HP-Andover-om1.om.hp.com
Date: Tue, 12 Oct 1999 08:20:22 -0400
Subject: FW: COZY: Pre-build: epoxy danger.

Wydo van de Waerdt writes;

> Is there still a possibility of getting an allergic reaction, 
> when taking all safety rules on epoxy in account ??

Take a look at the archives at:

   http://cozy.canard.com/mail_list/

and read the files regarding epoxy information for the past 5 years.

The short answer is "yes".  No matter what you do, there's still the small 
possibility that you'll have an allergic reaction.  However, the better the 
precautions that you take, the smaller the chances.  In the 5 years the list 
has been around, I've only heard of two people that had to stop building due to 
their allergic reaction even though they had take proper precautions.  This is 
out of about 300 - 400 builders.

--
Marc J. Zeitlin         marcz@ultranet.com
                        http://cozy.canard.com

    Non Impediti Ratione Cognitanis (C&C)

From: "Larry & Jenny Schuler" <lschuler@g2a.net>
Subject: Re: COZY: Cozy:  Epoxy mixing
Date: Sat, 9 Oct 1999 10:33:21 -0500



> I recently purchased a small mixer, designed for paints, and I would
>like to try to use it for mixing epoxy.  My problem is to use it with my
>drill press I am going to have to slow down the rpm's-  way below the
>slowest possible speed of the drill press.

Something to think about before going down that road:  It is very important
that the sides and bottom of the mixing container be scraped as part of the
mixing process.  Those portions of the mix need just as much mix time (three
minutes by hand) as the rest of it.

I cut the rounded end of the toung depressors off to provide a flat for
scraping the bottom and getting into the bottom corner of the mixing cup.

Larry



Date: Wed, 13 Oct 1999 15:17:18 -0400
From: kent ashton <kjashton@vnet.net>
Subject: Re: COZY: Pre-build: epoxy danger.

I bought a canard airplane from a guy who had built the whole airplane
(he said) with the RAE expoxy system and never wore a glove or used any
protection and didn't have a problem.
    Then he started on a Glasair and was doing layups inside the tail
without protection and began to get clots in his legs.  Thought he was a
goner.  He's a believer, now.
    I have found the MGS epoxy will give me a rash very quickly if it
gets on my bare skin.  I have had any problems with the RAE-types or
Safety-Poxy.

--Kent A.


From: Moparofer@aol.com
Date: Wed, 27 Oct 1999 19:32:43 EDT
Subject: COZY: Epoxy

Hello all. This is my first posting to the BB as I have just begun to build 
Mark IV # 0830. I have read the education section thouroughly and believe I 
have a reasonable understanding of what goes on. However when I called Wicks 
today I discovered that that have neither RAE epoxy nor Epolite epoxy. Which 
of their materials are comparable and/or which do you all presently use? 
Thank you in advance and happy flying. 
Ofer Nadel
Woodstock, Ga.
Mark IV #0830

Date: Thu, 11 Nov 1999 09:16:54 -0600
From: "David Burkes" <david@saffairs.msstate.edu>
Subject: COZY: Epoxy system

Hello,
I am trying to determine which epoxy system to use.After much
gleaning of information, I have determined I like the MGS system
of epoxy offered by Wicks. My questions are as follows...
1) Does L335 "MELT" after cure at a lower temp than L285?
2) L285 is thicker, and therefore harder to work with?
3)  Is the strength the same for both?

My concern is that I live in the deep south and 100+ deg
is not unusual. Your input/experiences is appreciated.

David Burkes plans #837- prebuild


Date: Thu, 11 Nov 1999 10:03:21 -0600
From: Michael Pollock <michael.pollock@wcom.com>
Subject: RE: COZY: Epoxy system

David Burkes wrote:

>I am trying to determine which epoxy system to use.

Hello David,

I live in the Dallas area where the temperatures get quite hot!  I am using
AeroPoxy for my Cozy MKIV and am very pleased with the results of the epoxy.
Also, it is less expensive than most of the other epoxy out there.  It does
have its drawbacks, such as moisture sensitivity and temperature range of
workability.  However, here in Dallas, it is quite easy to deal with those
things.  The humidity problem is corrected by using my air conditioner and
the temperature needs to be at least 75 - 77 degrees F. for good
workability.  Again, that is no problem here in Dallas.  In the winter, I
use a heater to keep my shop warmed to 75 degrees.  Just my 2 cents worth.

Michael.Pollock@wcom.com
Flying Velocity N173DT
Building Cozy MKIV #643


From: Ian Douglas <douglasi@sympatico.ca>
Subject: RE: COZY: Epoxy system
Date: Thu, 11 Nov 1999 21:18:49 -0500

I'll second the Aeropoxy recommendation.  I have been using it with good 
results.  The only time I have ever had any problems is when the humidity 
is very high >80%.  I use a hair dryer when wetting out the cloth (in 
Ottawa Canada) and then pump up the temp to around 90 deg. over night and 
the next day while it cures.  The following evening I am able to sand, pull 
peel ply etc.  The cost is much lower than any of the others and if you get 
the 5gal pale kit from Wicks, you will find that the price is cheaper than 
you can get it direct (by about $100.00).

Ian Douglas
working on the turtle back and control system.

From: "John Slade" <rjslade@bellsouth.net>
Subject: Re: COZY: Epoxy system
Date: Thu, 11 Nov 1999 21:48:04 -0500

Was said (twice)
>The cost [of aeropoxy] is much lower than any of the others
I'm not sure about this. With MGS I seem to be using about 60% of the plans
recommended epoxy quantities. e.g. winglets done and 3/4 of the way through
wings on less than 2 gallons. Bottom line cost may be considerably less with
MGS, even if cost per gallon is higher. Also part weights are low.

my 2c.

Just finished my second wing bottom skin (without any helpers).

John Slade
Cozy MKIV #757, http://kgarden.com/cozy



Date: Fri, 12 Nov 1999 08:23:47 -0600
From: Michael Pollock <michael.pollock@wcom.com>
Subject: RE: COZY: Epoxy system

John Slade wrote:
>Bottom line cost may be considerably less with
>MGS, even if cost per gallon is higher. Also part weights are low.

I too am quite a bit ahead of the plans quantity suggestion.  Let's wait
until the airplanes are finished and then compare.  Also, my parts weights
are much lower on this airplane than on the Velocity that I built earlier.
Maybe I have learned how to get the right amount of epoxy/cloth ratio.
However, I am spending much less money now on Aeropoxy than I was on the
Hexell epoxy I used on the Velocity.


Date: Fri, 12 Nov 1999 13:36:51 -0600
From: Michael Pollock <michael.pollock@wcom.com>
Subject: RE: COZY: Epoxy system

Nat Puffer wrote:

>Michael,

>The Velocity is normally 250 lbs heavier than the Mark IV. Maybe that's
>where all the epoxy goes.

Nat,

I know how much the Velocity weighs in comparison to the Cozy, and I also
know that the total area is much more on the Velocity than the Cozy.  I was
speaking of glass over foam (the same size of foam and number of layers of
glass on a specific piece) comparisons.  One cannot compare the total weight
of a Velocity to the Cozy in the number of gallons of epoxy one uses.
Measuring apples to apples, I am getting about 10% less weight per size of
layup with the Aeropoxy than the Hexel.  Also, the Aeropoxy is about 36%
cheaper per gallon than the Hexel that I used.

Michael.Pollock@wcom.com
Flying Velocity N173DT
Building Cozy MKIV #643



From: Epplin John A <EpplinJohnA@jdcorp.deere.com>
Subject: RE: COZY: Epoxy system
Date: Fri, 12 Nov 1999 13:53:52 -0600



> -----Original Message-----
> From:	Michael Pollock [SMTP:michael.pollock@wcom.com]
> Measuring apples to apples, I am getting about 10% less weight per size of
> layup with the Aeropoxy than the Hexel.  Also, the Aeropoxy is about 36%
> cheaper per gallon than the Hexel that I used.
> 
> 
	[Epplin John A]  
	I can believe that.  I also expect you will get lighter yet parts
with MGS.  I did not make two identical parts and weigh them but it seems
the lower viscosity would produce lighter parts.

	John Epplin   Mk4  #467,  still priming and sanding.

Date: Fri, 12 Nov 1999 14:48:13 -0600
From: Michael Pollock <michael.pollock@wcom.com>
Subject: RE: COZY: Epoxy system

John Epplin wrote:

>I can believe that.  I also expect you will get lighter yet parts
>with MGS.  I did not make two identical parts and weigh them but it seems
>the lower viscosity would produce lighter parts.

I did not use an epoxy heat box on the Velocity.  I am using one on the Cozy
and the viscosity is definitely lower at 100 degrees F.  It is quite easy to
wetout with the Aeropoxy.  The only drawback I can see (or better yet, not
see) is with the Aeropoxy peach color.  It is difficult to see that a whole
piece of glass is properly wetted out.  I generally apply way too much epoxy
and then use the squeegee to remove the excess.  How much does the MGS cost
verses the Aeropoxy?

Michael.Pollock@wcom.com
Flying Velocity N173DT
Building Cozy MKIV #643
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Epplin John A wrote:

> > -----Original Message-----
> > From: Michael Pollock [SMTP:michael.pollock@wcom.com]
> > Measuring apples to apples, I am getting about 10% less weight per size of
> > layup with the Aeropoxy than the Hexel.  Also, the Aeropoxy is about 36%
> > cheaper per gallon than the Hexel that I used.
> >
> >
>         [Epplin John A]
>         I can believe that.  I also expect you will get lighter yet parts
> with MGS.  I did not make two identical parts and weigh them but it seems
> the lower viscosity would produce lighter parts.
>
>         John Epplin   Mk4  #467,  still priming and sanding.

Don't you also need to consider compression forces where less epoxy could  be
TOO LITTLE.  When I first started I made the "test bar" suggested in the plans.
I put it over a bar and balanced my 200 pounds over it with a foot on each side.
after the fourth cycle it failed by compression of the bottom.  The epoxy I use
is West  (like Rutan's) and has excellent values for tension, compression and
higher than the average of most others in torsional and peeling.  However
because it is less viscous it wets the glass very quickly and can be applied too
lightly.  This problem is addressed in Chapter #3,  pg. 12, detail 3.  I do want
to see you succeed.
Joe

Date: Thu, 18 Nov 1999 21:34:56 -0500
From: siegler@charm.net (Stuart Siegler)
Subject: Re: COZY: Re: epoxy curing - cold temps.

I have found that once you bring the temp back up to the correct
range, 70 -90ish for a reasonable amount of time, that the epoxy
cures correctly.

Has Gary chimed in here on this issue?  He is the expert!

Stuart


>Wow,
>        The following message from that other email group unsettles me.  Some of
>my initial cures were in the cold, say around 50 deg.  Any thoughts from
>the group?
>Dana Hill
>CZ IV #676 
>
>--------- Forwarded message ----------
>Militch@aol.com wrote:
>
>> The epoxy can cure over a very long period.  I let mine cure at
>whatever
>> ambient temperature is.  My garage can drop to 40 or 50 degrees at
>> night, but the layups are generally ok by the next afternoon when I
>come
>> back to examine my work. Sometime in the next year or so, during the
>> summer, my garage will hit 120 degrees.  Further curing will no doubt
>> take place at that time.
>
>We tested all kinds of resin systems.  We let some of them over night
>cure at low temps down to 60 degrees.  We then tested them after post
>cure and found the Tg could be 40 degrees less than what the manufacture
>claims on the product.  Try to never let the overnight cure go below
>70 degrees.  You will be happier with the results. 
>-- 
>Jeff Russell/AeroCad Inc.     

--
Stuart Siegler
siegler@charm.net
http://www.charm.net/~siegler/

... and we're gonna keep on having meetings 'till we find out why nothing's getting done here.


From: "Rick Maddy" <cozy@maddyhome.com>
Subject: COZY: Exotherm and MGS
Date: Wed, 1 Dec 1999 23:07:27 -0700

I got some great first hand experience at an exotherm tonight. I was doing
the second practice layup - the "Confidence Layup". I had finished laying up
the 2 plies UNI and the 2 plies BID. After I applied the slurry over the
foam I noticed the other cup with the plain (or is that plane ;) ) epoxy
looked funny. I picked it up and the cup had a big clump in it. Then I felt
the heat through my butyl gloves. Then I noticed the steam. Boy was it hot.
My shop was about 78 degrees and there was about 4 or 5 oz. of epoxy in the
cup. I wasn't sure if the cup was going to melt so I quickly set the cup
outside where it is only about 40 degrees.

It was pretty neat. Time for smaller batches.

I was also surprised at how quickly the cup of slurry turned into a rock.
I'm using MGS epoxy.  The slurry was about 40% micro balloons and the
hardener was about 40% fast and 60% slow.  From initial mixing to being
fairly solid was about 30 minutes.

Rick Maddy  (cozy@maddyhome.com)
Cozy Mk IV #0824: Chapter 3 (www.maddyhome.com/cozy)

From: "John Slade" <rjslade@bellsouth.net>
Subject: Re: COZY: Exotherm and MGS
Date: Mon, 29 Nov 1999 09:15:22 -0500

>Time for smaller batches.
Not really, Rick. There are lots of jobs where you'll need a half cup or
more of epoxy every few minutes. You just need to get it out of the cup
quicker.

>From initial mixing to being
>fairly solid was about 30 minutes.
That's you're mistake. If the epoxy comes out of a hot box you only have a
few - say 10 max - minutes to get it out of the cup and spread on the part.
By the time you do the fuselage sides in Chap 5 you'll be squirting &
spreading epoxy like a banchee!  I do a very fast brush stroke all over the
part without looking for wet up - then, once the cup is gettng empty and the
epoxy has had time to soak, I go back and check for any areas I missed.
Better to have too much than too little.

As you move onward, try experimenting with different hardner ratios. All
slow makes a BIG difference. I keep my hardner level in the pump fairly low
and dump a bit of hard or slow in depending on the job. You'll get a feel
for how much to "dump in" based on how quick you get an exotherm [you'll see
plenty of these] and how quickly the epoxy looses viscosity.  As far as I
know, the only reason to use fast hardner is to save waiting time for cure.
Using all slow all the time would be a drag. As you move into bigger parts
I'd suggest ordering more slow than fast. Two pumps would be real nice.

Have fun

Regards,
John Slade


From: "cliffordfamily" <cliffordfamily@provide.net>
Subject: Re: COZY: Exotherm and MGS
Date: Thu, 2 Dec 1999 03:26:51 -0500

Rick,

We have been using the MGS epoxy from the start.  We also started with a mix
of fast and slow hardener and quickly learned  that exotherm can be a real
problem.  We now only use the slow hardener.  It gives us ample time to work
with a batch and we have not had a need for the fast hardener so far.  The
epoxy always kicks sooner when you add micro or flox also.

Dave #656
Mike & Thane #591
Well into chapter 8 on both planes side by side

From: Militch@aol.com
Date: Thu, 2 Dec 1999 22:17:38 EST
Subject: Re:  COZY: Exotherm and MGS


In a message dated 12/2/99 1:13:55 AM, cozy@maddyhome.com wrote:

>My shop was about 78 degrees and there was about 4 or 5 oz. of epoxy in the
>
>cup. I wasn't sure if the cup was going to melt so I quickly set the cup
>
>outside where it is only about 40 degrees.
>
I'll bet you were using the 285 hardener.  If you need to make a big batch of 
epoxy, use the 287. If you want it to last a bit longer, but still want it to 
cure well by morning, use a mix of 285 and 287.

Regards

From: "Hunter, Gary GA SCC" <GH334766@MSXSCC.shell.com>
Subject: COZY: RE: Epoxy aging?
Date: Mon, 6 Dec 1999 09:46:26 -0600 

Neil Clayton wrote: 

> 	Question for the group, especially Gary Hunter....can anyone shed
> some
> light on an epoxy issue for me?
> 
> Does epoxy have a shelf life? And what are it's traits towards the end of
> that life?
> 
> I use 4426A Resin with 9377 Hardener and have been happy with it (vs the
> old 2427 junk). The current batch is about 4-6 months old (since can
> opening). The resin has developed a cloudy appearance and is clogging up
> the dispenser valve (I have to jiggle it each time with a screwdriver tip
> to loosen the valve before dispensing). The mix has a milky consistency to
> it, and it takes a longer time to set (>48hrs, vs 24 hrs normal). I did a
> test pot using mix and flox and there was a pliability to it at first,
> then
> a brittleness after a week or so. I'm dumping it and buying new but I'm
> interested in the chemistry of this stuff. I've been careful not to use it
> on critical locations while in this condition.
> 
I responded directly to Neil Clayton with copies of previous posts on this
subject. 

In short - What you are experiencing is resin crystallization.   Epoxy
resins never go bad... or run out of shelf life.   Epoxy resins can be
reconstituted by warming to 120F or so.  You should never use epoxy resin in
the crystalized state.  

Kindest Regards,

Gary Hunter

From: Fritzx2@aol.com
Date: Mon, 6 Dec 1999 16:55:37 EST
Subject: Fwd: COZY: RE: Epoxy aging?

Gary Hunter wrote,

>Epoxy resins never go bad... or run out of 
>shelf life.   Epoxy resins can be reconstituted 
>by warming to 120F or so.  You should never use 
>epoxy resin in the crystalized state.  

I thought that Rutan recommended only keeping
the epoxy for 1 year.  I'm not sure if this
was 1 year in a pump that is vented to the
atmosphere or 1 year in a can on the shelf.
I'm assuming that what you refer to as "resins"
is what I normally call the resin and the
hardener together.  Has the evolution of
epoxy that started out with a shelf life of
1 year evolved to the point to where we now
no longer need to be concerned with using
epoxy that is older than 1 year?  Does this
apply to all types of epoxy generally in use
today or only certain types.  For instance,
I'm using the EZ poxy that replaced the 
Safe T Poxy.  Kind of interested since I
have some EZ poxy that sat on the shelf
unopened for 8 months inside the house,
heated it up to 120 F for a couple of
hours before first using it, and now 
4 months later (1 year since I ordered it)
have about a half a gallon left and it
is time to do the spar caps and skins of
the canard.

Gary, thanks so much for all your help regarding
epoxies (the nuts and bolts of our planes).

John Fritz
fritzx2@aol.com

Date: Mon, 06 Dec 1999 17:53:31 -0500
From: Jeff Russell <JRaero@gte.net>
Subject: COZY: epoxy hardener?

Fritzx2@aol.com wrote:
> 
> Gary Hunter wrote,
> 
> >Epoxy resins never go bad... or run out of
> >shelf life.   Epoxy resins can be reconstituted
> >by warming to 120F or so.  You should never use
> >epoxy resin in the crystalized state.
> 
> I thought that Rutan recommended only keeping
> the epoxy for 1 year. 

Gary, correct me if I am wrong, but I think you were saying the 
epoxy resin won't go bad but the hardener can and will with
moisture and other impurities over time.  I have never had the 
resin go bad but I have see the hardener on the 2427 and aeropoxy
not work correctly even after heating over and over again after
it went milky in color.  Peel and Tg went to hell on samples
so the cure to this was get new "stuff" or a resin system that did not
have a water issue.  EZpoxy or the old Safe-T-poxy hardener
never gave us any problems except it stinks.


-- 
Jeff Russell/AeroCad Inc.                    E-mail:   Jeff@aerocad.com
2954 Curtis King Blvd.  Ft. Pierce, FL. 34946
Shop# 561-460-8020 7:00am to 3:30pm  Home# 561-344-6200
Website:   http://www.Aerocad.com
Composite workshop info:   http://www.Sportair.com

-- 
Jeff Russell/AeroCad Inc.                    E-mail:   Jeff@aerocad.com
2954 Curtis King Blvd.  Ft. Pierce, FL. 34946
Shop# 561-460-8020 7:00am to 3:30pm  Home# 561-344-6200
Website:   http://www.Aerocad.com
Composite workshop info:   http://www.Sportair.com

From: "Hunter, Gary GA SCC" <GH334766@MSXSCC.shell.com>
Subject: COZY: Epoxy Aging / Shelf Life, etc.
Date: Tue, 7 Dec 1999 07:24:16 -0600 

Let me try to make this as clear as possible.   When the general population
speaks of "epoxy resins" they tend to generically refer to both the resin
and the hardener.   In my world, when we refer to both the resin and
hardener it is called a "resin system".    HOWEVER,  the resin and hardener
are two separate things and from a storage or shelf life perspective need to
be addressed separately.  Below is page 37 from my forum at AirVenture 99

What is the shelf life for resins and curing agents ?

*	Some formulators state one year - it sells more resin.

*	Properly formulated resins will keep forever if stored properly.
*	Tightly sealed containers @ 70 +/- 15F

*	Most curing agents will keep forever if stored properly.  
*	Tightly sealed containers @ 70 +/- 14F
*	Direct sun light will cause darkening - brown

*	Exception - EZ-Poxy 83, 84, 87 may increase in viscosity if storage
temperatures are too high (per CPD)
*	Refrigeration WILL enhance shelf life.

Now - to further elaborate.  - And, I hope this doesn't become another
information overload - Nat.

Some formulators will mark the containers and limit shelf life for a variety
of reasons.  One - It helps to separate them from liability.  Two - It helps
them sell more resin.   Three - It keeps them from being pestered with the
same question - Is it still good ?   From a responsible care perspective -
our company forbids such practice - it makes for unnecessary chemical waste
that further pollutes our environment.  

"Properly formulated resin" - I had to use this qualifier because there are
some things a formulator can do to destroy the inherent shelf stability of
the epoxy resin.   However, as far as I can tell, all the epoxy resins we
have to our avail utilize industry acceptable formulating practices.   The
temperature is merely a range that is typically found in most warehouse
storage conditions.   We store our resins in huge tanks at 180F all year
long prior to drumming off or tanker car loading.  Many of our bulk
customers store their resin at 120-140F all year long.   We do this ONLY to
obtain a pumpable viscosity.   I mention this to illustrate that warming
your resin won't hurt it.   Refrigerated storage is not necessary and will
accelerate crystallization of the resin.   DO NOT use resin in the
crystallized state.  Simply warm the resin to about 120-140F until all the
crystals are melted.   

"Most" curing agents - I say "most" as a qualifier again because there is an
exception.   The most important thing about curing agents is a tightly
sealed container, as they will absorb moisture and react with CO2.   Storage
temperature is bit more critical too - but, refrigeration is not necessary.
Excessive heat and/or direct exposure to sunlight will cause most curing
agents to darken or turn brown.  However, the discoloration will not hurt
anything performance wise.  Furthermore, most of the curing agents we have
to our avail contain some amount of volatile materials that may evaporate
with excessive heat.  The primary ingredient of the curing agent itself is
susceptible to volatilization too.   So, keep unused curing agents in
tightly sealed original containers in cool conditions and everything will be
fine.   Those of you using epoxy pumps with open style reservoirs should
consider closing them tightly when not in use.  Warm them and vent them only
when needed for pumping.  A nitrogen or argon (from your welding rig)
blanket on top of the curing agent in the reservoir would be ideal - but not
absolutely necessary.   Some of these hardeners will form a white crusty
crystalline looking substance around the container cap or pump dispenser
nozzle.  This is the by-product of the curing agent reacting with CO2.  It
WILL NOT dissolve back into the curing agent or resin.    But, it will wash
off with water.  

The Exception - EZ-Poxy hardeners 83, 84 and 87 (formerly Safe-T-Poxy) may
increase in viscosity if storage temperatures are too high for too long - in
excess of 100F.  This is per the manufacturer - Composite Polymer Design.
Refrigeration will retard viscosity growth of these hardeners.   An EZ-Poxy
hardener that has grown in viscosity, either from excessive heat or simply
long term storage, will perform the same when cured.   It just won't wet the
fabric as quickly because of the increase viscosity.   EZ-Poxy hardeners can
crystallize too.   DO NOT use these hardeners in the crystallized state.
Warming them to 120F for a brief period of time will de-crystallize or
reconstitute the hardener to a useable state again.  

Kindest Regards,

Gary Hunter
Technical Service Representative
EPOXY RESINS TECHNICAL INQUIRY
SHELL CHEMICALS, USA


