From: Jim Hocut 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 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 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 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 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" 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" 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" 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" 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 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" 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 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 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" 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 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 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 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 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 From ???@??? Sat Nov 13 12:54:38 1999 Return-Path: owner-cozy_builders@betaweb.com Received: from twc2.betaweb.com (majordomo@betaweb.com [206.43.209.18]) by acestes-fe0.ultra.net (8.8.8/ult/n20340/mtc.v2) with ESMTP id UAA14294 for ; Fri, 12 Nov 1999 20:57:28 -0500 (EST) Received: (from majordomo@localhost) by twc2.betaweb.com (8.8.5/8.8.5) id UAA06786 for cozy_builders-list; Fri, 12 Nov 1999 20:08:52 -0500 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from mail.rdc1.ab.home.com (imail@ha1.rdc1.ab.wave.home.com [24.64.2.50]) by twc2.betaweb.com (8.8.5/8.8.5) with ESMTP id UAA06781 for ; Fri, 12 Nov 1999 20:08:45 -0500 Received: from compusmart.ab.ca ([24.66.215.229]) by mail.rdc1.ab.home.com (InterMail v4.01.01.07 201-229-111-110) with ESMTP id <19991113010250.EHCS25308.mail.rdc1.ab.home.com@compusmart.ab.ca> for ; Fri, 12 Nov 1999 17:02:50 -0800 Message-ID: <382CB77B.FBC572A2@compusmart.ab.ca> Date: Fri, 12 Nov 1999 17:57:31 -0700 From: "Capital Steel Inc." X-Mailer: Mozilla 4.7 [en] (Win98; I) X-Accept-Language: en MIME-Version: 1.0 To: "cozy_builders@canard.com" Subject: Re: COZY: Epoxy system References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: "Capital Steel Inc." X-UIDL: 7dce22146d1188275b1c80ee17369259 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" 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" 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" 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" 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 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" 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