From: "ZEITLIN,MARC (A-Andover,ex1)" Subject: FW: COZY: Epoxy melting foam? Date: Mon, 10 Jan 2000 06:09:31 -0700 > You are correct, Marc, polyester and vinylesters contain styrene monomer is > such quantities that it will dissolve or melt the blue foam. Styrene > monomer is a natural solvent for polystyrene. Polyester and Vinylesters > are not approved for Cozy construction and as such, problems relating to > melting foam should not occur. > > The epoxy resins approved for Cozy construction "should not" harm the blue > foam in any way. This is not to say, ALL epoxies will not hurt blue foam. > It is entirely possible for other brands of epoxy resin to damage the blue > foam. It all depends on the specific formulation. Therefore, you should > adhere to the designers list of "tested and approved" resins for the > construction of your project. > > Additionally, one should never attempt to "improve" the wetout > characteristics of your resin through the addition of solvents like lacquer > thinner, or even alcohol. Styrofoam is susceptible to attack from many > different kinds of solvents. > > Kindest Regards, > > Gary Hunter > Technical Service Representative > EPOXY RESINS TECHNICAL INQUIRY > SHELL CHEMICALS, USA From: "ZEITLIN,MARC (A-Andover,ex1)" Subject: FW: COZY: Epoxy melting foam? Date: Mon, 10 Jan 2000 08:16:48 -0500 > The old Hexcel 2427 Resin and EZ-10 are the same thing. The hardeners are > the different. EZ-83 thru 87 are the old Saf t poxy systems. These systems > are made with a small amount of styrene monomer to etch the blue foam for > bonding. The micro slurry mixture screeded into the foam is to inhance the > fabric's bond to the foam. The problem most people have with the resin > system "melting" the foam is exotherm. The older the 2427 hardener the > "hotter" the reaction. Also some other systems have pretty hot hardeners > like TEDA and DETA as their backbone because they are cheap. Rules of thumb > 1) older hardeners adsorb moisture and make the system more prone to > exotherm in small masses. > 2) the cheaper the hardener the more likely it's a short chain aliphatic > amine hardener backbone and therefore hotter exotherms. > 3) if you live in a humid climate the more likely it will be a "hotter" > reaction and you should use a slower system for most laminates like EZ-10 > and EZ-87. > Thanks Gordon From ???@??? Thu Jan 27 22:27:53 2000 Return-Path: owner-cozy_builders@betaweb.com Received: from alum.mit.edu (ALUM.MIT.EDU [18.72.0.38]) by acestes-fe0.ultra.net (8.8.8/ult/n20340/mtc.v2) with ESMTP id JAA20962 for ; Thu, 27 Jan 2000 09:59:56 -0500 (EST) Received: from twc2.betaweb.com (majordomo@betaweb.com [206.43.209.18]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id JAA15879 for ; Thu, 27 Jan 2000 09:59:56 -0500 (EST) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id JAA02488 for cozy_builders-list; Thu, 27 Jan 2000 09:06:28 -0500 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from mail1.mia.bellsouth.net (mail1.mia.bellsouth.net [205.152.16.13]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id JAA02479 for ; Thu, 27 Jan 2000 09:06:20 -0500 Received: from amd300 (host-209-215-54-193.pbi.bellsouth.net [209.215.54.193]) by mail1.mia.bellsouth.net (3.3.5alt/0.75.2) with SMTP id JAA02223 for ; Thu, 27 Jan 2000 09:02:12 -0500 (EST) Message-ID: <078801bf68ca$aa69b4c0$c9f6fea9@amd300> From: "John Slade" To: "Cozy builders" Subject: COZY: Epoxy - yellow tinge to MGS resin Date: Thu, 27 Jan 2000 08:30:22 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.1 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: "John Slade" X-UIDL: 318a283057528eb605ffa1962c9dd63e Builders. I recently received a batch of MGS resin which had a slight yellow tinge to it. Wicks said this was normal, and not to worry, but I emailed MGS in Germany, just to be sure. I received a reply from the man himself, Martin Scheufler, today. Here's the correspondence: John Slade, Cozy MKIV #757, progress: http://kgarden.com/cozy West Palm Beach, FL >>just received a shipment and one gallon (batch 820036) has a slight yellow color. >>All the other resin I've received has always been clear. Should I use this resin or return >>it for replacement? >The colour of resin L 335 is specified with GARDENER max 3. So any colour of clear >like water - yellow (GARDENER 3) are in the specified range and can be used without >any problems. The colour of the hardeners can verify also, depending of the colours of >the raw materials and this is absolutely no indication for changing quality of the products >Best regards >Martin Scheufler From: "Nat Puffer" Subject: Re: COZY: Epoxy Issues Date: Wed, 29 Mar 2000 11:28:39 -0600 ---------- > From: Hunter, Gary GA SCC > To: 'Rick Maddy' ; 'Cozy Mailing List' > Subject: RE: COZY: Epoxy Issues > Date: Wednesday, March 29, 2000 9:16 AM > > Rick wrote: > > > The good news is that my pump seems virtually perfect. I assume 45.6:100 > > is > > close enough to 45:100. > > > YES that is close enough - IF - the weight ratio is supposed to be 45/100. > But as you later found out - the ratio should be 38/100. +/- 2 > (according to MGS literature the - maximum allowable is 40/100). THIS IS A > SERIOUS ERROR There seems to be some confusion here. Metering pumps measure by VOLUME, because they rely on volumetric displacement. The volume ratio for MGS 335 is 45:100. The volume ratio for MGS 285 is 50:100. If you are checking your metering pump by weighing how much of each it dispenses, then you check weights by using the weight ratios: The weight ratio for MGS 335 is 38:100 The weight ratio for MGS 285 is 40:100 Regards, Nat > From: "Hunter, Gary GA SCC" Subject: COZY: Epoxy Issues Date: Thu, 30 Mar 2000 09:27:32 -0600 > Gary wrote - > "...you must thoroughly mix them before use." Chris asks - I use a pump, (checked for accuracy regularly) and often pour in a bit more slow or fast hardener. I stir it a small amount, but not as much as if mixing a batch of epoxy. Some stirring is definitely better than no stirring. But, in my professional opinion - you should cease the practice of adding a little of fast, or a little of slow to adjust the cure speed at will. This is not considered an acceptable practice anywhere in the epoxy composites industry. You should pick a blend ratio that you are comfortable with and stick to it. Nat suggests a 50:50 blend to be just about right for him. There a number practical and technical reasons why. More on that later. Not to beleaguer everyone again with my views on balances vs. pumps, but if you use a balance, you could have separate containers for your favorite curing agent blends to choose from when you go to mix a batch. Clearly labeled - Slow, Medium and Fast. (75:25 / 50:50 / 25:75, slow:fast). Now, instead of hoping you get the blend you want and wondering why you didn't, you get exactly the blend you want - no guess work involved. HOWEVER, I suggest that you stick with one blend ratio to build an entire major structural component. For instance, you might use the slow for laminating the main wing spars. But, you should use the slow for BOTH wing spars. And, it would acceptable to switch to the medium for laminating the wing skins - but you should stick with the medium for both left & right wing skins / top & bottom. Do not change mid-stream. If temperature conditions in shop temps you to change the curing agent blend ratio, I prefer you adjust the shop temperature instead. The fast curing agent blend would be most useful in areas that don't require long working time like taping of bulkheads, and seams and other small jobs. > I would have thought that it would not have affected the layup if the two > hardeners had not been mixed in the pump at all, after all the correct > ratio > of hardener/resin still ends up in the cup, and if you pumped in mostly > fast > hardener(due to not mixing it) it would cure a lot faster than you may > have > otherwise anticipated but the layup would still be structurally sound. > Yes, you are technically correct in that you will still have the correct mix ratio. And theoretically, the lay-up should be structurally sound too. But, no one has ever tested and proven that to be true. >From my perspective, the chemical composition of these two hardeners are different enough to produce slightly different physical properties - tensile, flexural, compressive strength - elongation and impact resistance, etc. The MGS literature simply reports a rather wide range (10-25% of the mean) on these physical properties that I presume is intended to cover both extremes and the standard deviation. They don't report separate strength figures for the slow and the fast hardeners. Nevertheless, imagine if you will - a wing laminate made from a hodge podge of curing agent blends under a black light in which the slower curing agent blends glow more than the faster blends. The laminate would look like a calico cat. Brightly glowing spots softly blending into darker spots representing the different physical properties of the resin. Sort of like a bad batch of 2024T3 aluminum sheet, with spots of 6061T6 and 5052H32 blended in at different places. Of course, much like the resin system of topic, all of these grades of aluminum are structurally capable of the job, but this hodge podge blend of aluminum grades is not acceptable from an engineering point of view. Nor should the hodge podge epoxy composite be acceptable. Of course that's my professional opinion - I could be wrong. Gary Hunter From: "Hunter, Gary GA SCC" Subject: COZY: 5 minute epoxy fuel resistance Date: Tue, 4 Apr 2000 07:16:07 -0500 Jim Marshall asked me: Question is about whether AVGAS will deteriorate the 5-MIN Epoxy. The hardener is the big difference here. The resin side tends to be a neutral in most comparisons. Generally, the 5-min stuff is not intended for such uses and little is known about it's long term AVGAS or MOGAS resistance. Henkel Corporation makes the two hardener components that are blended together to make the five minute epoxy hardener. Depending on the ratio of the two hardeners you get 5, 10 or 15 minute epoxy. Henkel reports some short term testing (16 weeks immersion in gasoline - presumably mogas) on a hardener blend that is slightly different from the typical 5 minute variety. It looked pretty damn good. About 1.0 % weight gain and no change in hardness. General, AVGAS is less aggressive than MOGAS. Now keep in mind, that laboratory studies are just that - precisely weighed amounts of resin and hardener with exacting mixing and curing conditions. In our situation, we usually "eyeball" a 50:50 mix ratio and go with it. Precision does have an effect on the finer qualities of a resin system - particularly chemical resistance. If I were you, I would conduct my own test. Whoop up some 5 minute flox and cure it onto a piece of soft aluminum and fiberglass to mimic the bonding of fittings and tubing into a fuel tank. Allow it to cure under normal room temperature conditions for at least 2 weeks. Then immerse it in jar of AVGAS and/or MOGAS and observe changes in color, hardness and adhesion to the aluminum. If all is well after 30 days or so, chances are everything will be find for several years. Another option is ask System Three if they have any experience with 5 minute epoxy and gasoline. Gary Hunter Date: Mon, 17 Apr 2000 05:54:42 -0700 (PDT) From: Terry Winnett Subject: COZY: MGS Epoxies Fellow builders, For those of you using MGS expoxies, I found out some interesting tidbits on the system and the company from the nice folks in Stuttgart. I ran into a problem when I let my resin get cloudy (without noticing) and did a layup on the seatback brace and heat ducts. The epoxy was still rubbery 36 hours after I did the layup. Scratching my head, I looked at the resin tub and couldn't see through it. On the bottle it states, "Use Only Completely Transparent Resin". Ooops... I scrapped the layup, but was concerned about the upper longeron to fuselage side floxing that I did previously, so, I decided to call Deutschland. I talked to a Herr Batinger (who is a pilot) and explained my dilemma to him. My german skills from my tour there in the Army still served me well and he told me that moisture causes the resin to go milky and to heat it up to 40-50 degrees centigrade for a while to clear it up. I already scrapped the resin, so couldn't do that. Further, he said that the strength shouldn't be diminished, as long as the dispensing ratio is correct. Relieved, I asked about the company. It seems that epoxy systems for aircraft and US sales, period, are just a drop in the bucket compared to their main business, which is epoxy for laminating blades for wind turbines manufactured all over Europe. I thought this was fascinating. Anyway, hope you enjoyed the trivia, despite my long-windedness. Blue skies... Terry Winnett MkIV #792, Ch.5 (still) San Antonio, TX __________________________________________________ Do You Yahoo!? Send online invitations with Yahoo! Invites. http://invites.yahoo.com From: CozyBuilder@aol.com Date: Wed, 3 May 2000 15:32:30 EDT Subject: COZY: my reaction to glassing Last night I did quite a bit of glasswork, using mgs. I got home and didn't feel that great, and blew my nose and hmmm... blood. The night before, I did some glass work and there was blood too. Then I remembered when doing some glassing one day, the sunlight was shining in just right, and as I cut the glass, I could see many tiny fibers going airborne. After seeing the blood, I thought, hey, thats glass man, not naturally occurring like wood--sawdust. Up til now, I have not worn a mask at all during layups or cutting the cloth. I didn't see a need to as there was no strong smell from the epoxy like there is with MEK, or other paints, solvents, so I figured it was harmless due to the srtong lack of odor. Then again, maybe it is harmless. Maybe the blood was just from inhaling the fibers that go airborne when cutting the cloth and carrying it to the point of install. Who knows. I used to wonder why Rick Maddy had a picture of himself on his website doing a layup wearing a mask. I didn't see a need for it. Well, I'm joining him now. I can see it is very very important to wear a mask, as much as a pain as it seems, for the majority of the 2,500 hours. I'll just have to get used to it. Those of you who opt not to, hey that's fine, but realize, when the lighting is not perfect, you may not think youre inhaling a bunch of micro, but you are. It is so fine, you just LOOK at it and millions of bubbles are airborne. And the same thing for the glass. You are eating it. And based on my reaction, which was not allergic but physical, you shouldn't chance it. Jay #858 Escondido CA Finishing up ch 6 My Website http://www.cozybuilder.com Date: Wed, 03 May 2000 17:41:29 -0400 From: bil kleb Subject: Re: COZY: my reaction to glassing CozyBuilder@aol.com wrote: > > [..] I figured it was harmless due to the srtong lack of odor. [..] like carbon monoxide gas? ;) tyvek-suited, carbon-filter respirator wearer, -- bil From: "Rick Maddy" Subject: COZY: Epoxy Issues Date: Tue, 2 May 2000 21:27:04 -0600 You may recall I posted a message a few weeks ago about my epoxy pump ratio being off. I was concerned the parts I had made up to that point might not be any good. I measured my pump to be dispensing 45:100 by weight instead of 38:100 by weight for MGS system L335. I got a lot of good feedback from members of this group. I sent an email to Johannes Meunier at MGS in Germany describing my situation. At his suggestion I sent him some samples. This included a scrap from my landing gear bulkhead hardpoint from chapter 4, a scrap from the spar cutout in the fuselage side in chapter 5, and a scrap from the seatback brace in chapter 6. This week I received a letter from Johannes with a print out of some graphs of the glass transition temperature of the parts at room temperature (as I sent them) and what appears to be some sort of post cure. I don't claim to understand the graphs but the letter says it all: "The glass transition is a bit lower than for optimum mixing ratio, but is expected to still meet the 54 degree C requirement the system was developed for." Whew! I don't have to start over. I just wanted to publicly thank MGS and specifically Johannes for his help. This is a great company and they make a great product. Do yourselves a favor and verify your pump ratio. I have an adjustable pump and blindly set it based on the instructions. I assumed it would be correct. Verifying it with a scale is a worthwhile and simple sanity check. Rick Maddy (mailto:rick@maddyhome.com) Cozy Mk IV #0824: Chapter 6 (http://www.maddyhome.com/cozy) From: "Hunter, Gary GA SCC" Subject: RE: COZY: Epoxy Allergy Date: Mon, 12 Jun 2000 10:07:43 -0500 Neil Clayton wrote: After years of successfully using RAF "slow", in the last couple of weeks I think I've developed a strong allergy to it. .....snip.... ....snip.....what would you recommend? Safety-Poxy??? MGS??? And some general questions; Will it adhere to my existing RAF parts? What's it's allergy likelihood - (is "Safety Poxy " called that 'cos it's hypo allergenic?) Any downside to it - peel strength? Carcinogenic? Doesn't wet out well/viscosity. Pot life? Exotherms at low volumes? Hello Neil: I am not going to play doctor here, but, first of all, you should go to the doctor and get him to prescribe a topical treatment. TOPICORT (0.25% desoximetasone cream) has been reported to provide good results. I have been told by others that Safflower Oil applied to the area helps relieve the symptoms too. Another person informed me that drinking Kali or Cali Tea worked for him. Obviously, you have experienced an acute allergic reaction. HOWEVER, it may not be the epoxy resin that is causing the allergic reaction. The RAES and RAEF resin systems use aliphatic amine curing agents that are particularly capable of eye and skin irritation. The majority of allergic reactions associated with the use of epoxy resins is really related to the curing agent. So, in your case, it might be the curing agent that is causing the allergic response. If that is the case, then EZ-Poxy may be the cure (no pun intended) as it uses aromatic amines in the curing agent that have significantly less irritation potential. On the other hand, if you have become sensitized to the epoxy resin portion you will need to take certain measures to finish your project regardless of which resin system you decide to use. As another person posted on the forum, wearing a hood, with a positive pressure fresh air supply will do the trick. Hobby Air is a brand that is commercially available from the aircraft supply houses. The EZ-Poxy will be fully compatible with your previous resins systems. The downside to EZ-Poxy is as follows: It is little more viscous than some of the other systems and as result may wet out a little slower than some of the others systems. It has rather evident styrene monomer odor. Additionally, the curing agent is "based on" the aromatic amine - Methylene Dianiline (MDA) that has been identified as a human carcinogen by OSHA. However, the MDA in this curing agent is "complexed" with the other ingredients in such a fashion that is no longer pure MDA. Unlike most aliphatic amines, the aromatic amines have lower vapor pressure and do not tend to volatilize into the breathing air. The most significant route of exposure for the complexed MDA is dermal. Keep it off of you, just like you should with all the other resin systems anyway, and you will be fine. The upside of EZ-Poxy is as follows: Long track record, no peel strength problems, long pot life, relatively low exotherm, and fuel resistance. MGS is comprised of mostly aliphatic and cycloaliphatic amines that can cause irritation to the eyes and skin too. If in fact you are allergic to the curing agent, MGS would not be a good alternative for you. Gary Hunter EAA Technical Counselor From: cdenk@ix.netcom.com Date: Mon, 12 Jun 2000 20:44:04 -0400 (EDT) Subject: Re: COZY: Allergy Precautions On 06/12/00 16:47:22 you wrote: > > >I called an asbestos removal company here in Orlando and asked where they >got their space suits for their employees' protection during asbestos >removal jobs. They referred me to their supplier; Oramsco in Lakeland, >Florida, (800) 767 1225. > >After a long chat about the options, I bought a whole face respirator (3M, >series 6000) for $78, and he said he'd send a sample body suit and hood for >me to try. After that, the suits which are disposable, cost around $3 each, >or $70 for a box of 25. > >I'm also changing epoxy and adding bigger air circulation fans in the shop. > >I'll report on the outcome of all these precautions. >more at 11... >Neil C > > There are suppliers for this type of equipment located in most bigger cities. Look in the yellow pages for safety equipment, or as said above, look for asbestos, chemical/hazardous spill cleanup, etc. The EPA is probably not a good source, since they are careful not to recommend a particular supplier. From: "Hunter, Gary GA SCC" Subject: RE: COZY: Polyester to epoxy Date: Mon, 3 Jul 2000 13:25:19 -0500 Paul Stowitts wrote: It is my understanding that epoxy will not adhere well to polyester. Is there an intermediate product that can be used between the polyester and epoxy to give a good bond? Epoxies will bond to "prepared" polyester composites just fine. Typically, you simply abrade the surface just as you would for an epoxy to epoxy composite bond. The abraded surface allows for a "mechanical bond" in addition to the epoxy's inherent adhesive properties. Thus, people have been repairing polyester and vinyl ester based composites with epoxies for many years. They generally hold up longer. On the flip side of the coin, polyester resins do not have the same inherent adhesive properties of an epoxy. Polyester's (and vinyl esters for that matter) rely heavily on "chemical bonding" when bonding to themselves. However, when it comes to bonding to epoxies, they are not chemically compatible and must rely solely on "mechanical bonding" to the prepared surface. Thus, it is not as strong a bond as an epoxy to polyester bond, or epoxy to epoxy Bonding to polyester based gel coats is another story. Polyester based gel coats cannot be "prepared" for bonding like polyester composite surfaces. Therefore, an intermediate "tie coat" must be applied to the gel coat prior to any subsequent epoxy composite application. This tie coat promotes chemical bonding between the two incompatible resin types. I know of only two companies that sell a formulated "tie coat" specifically for this purpose. System Three, and Hawk-Eye Industries. http://www.systemthree.com/ http://www.duratec1.com I hope this is helpful. Gary Hunter EAA Technical Counselor From: "Keith Scull" Subject: Re: COZY: Polyester to epoxy Date: Mon, 3 Jul 2000 21:59:43 +0100 Answer YES Paul it all depends as so often is the case on where you intend to mix polyester and epoxy systems, in Europe the resin system I used to construct my plane is "polyester compatible" inasmuch that you are able if you wish to make a composite polyester and epoxy lay-up, I have never attempted this but the data sheets for the resin describe how to achieve this as follows, before the epoxy has cured sprinkle chopped strands of glass mat over the uncured epoxy then lay-up the next layer of cloth using polyester resin and wet it out as normal. If it is because you will be using a polyester based paint then things are somewhat different. Most auto paint finishes are polyester based and there adhesion to epoxy is questionable, the advice given to me was not to rely on a chemical bond only as provided by the paint but to arrange for a mechanical bond as well, I achieved this by sanding the filled airframe with 40 grit paper,both vacuuming and blowing off the bust with compressed air then spraying the complete structure with one coat of 2K filler primer with an adhesion promoter added, after flashing off for 15 mins a further 4 coats of 2K filler primer with 50% by volume of micro added, giving a 15 min flash off between coats, the primer is then left to cure for 24 hours (shorter in warm conditions) and sanded flat with a long block coated with 80 grit paper, all the low spots now show darker (the micro padded primer sands pale in colour) a further 4 coats of padded out primer was then applied and sanded flat again with a long block, the finished result is a completely flat and smooth finish ready for painting that has no low spots, no high spots, very good adhesion due to the course sanded mechanical bond and adhesion promoter and no scratches to show through your finished paint. It sounds like a lot of work but the filler primer is very soft at just one day cure and sands very easily to a beautiful finish and as you remove practically all you spray on it should not add any additional weight compared to additional micro and resin filler. Regards Keith Scull ----- Original Message ----- From: Paul Stowitts To: Cozy_Builders Sent: Monday, July 03, 2000 4:32 PM Subject: COZY: Polyester to epoxy > It is my understanding that epoxy will not adhere well to polyester. Is > there an intermediate product that can be used between the polyester and > epoxy to give a good bond? > > TIA > > Paul Stowitts > Cozy Mark IV N166PT (Officially) > >