From: GeneKnapp2 Date: Mon, 2 Mar 1998 12:21:04 EST Subject: COZY: Fuel Resistant Foams Question Does anyone know if PVC (H-45) is fuel resistant? I have been told that polyurethane foam does not hold up well in service. Anyone know about these two Questions or have been testing them in fuel for any length of time? Gene GeneKnapp2@aol.com Date: Mon, 2 Mar 1998 09:55:18 -0800 Subject: Re: COZY: Fuel Resistant Foams From: alwick@juno.com (ok How) I placed samples of glass layup and fuel tank foam in a mason jar filled with fuel. Replaced the fuel once with auto fuel known to contain alchohol. Foam not affected. Epolite 2427 not affected. Samples have been immersed for over a year now. I have no concerns. Rumors regarding 2427 fuel compatability totally unfounded. -al wick 70% comp. Cozy MkIV with stock Subaru 2.5 engine. Computerized cockpit. Just completed proto engine mount, now working towards engine ignite! On Mon, 2 Mar 1998 12:21:04 EST GeneKnapp2 writes: >Question > >Does anyone know if PVC (H-45) is fuel resistant? > >I have been told that polyurethane foam does not hold up well in service. > >Anyone know about these two Questions or have been testing them in fuel >for any length of time? > >Gene GeneKnapp2@aol.com > _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] Date: Mon, 02 Mar 1998 21:25:01 +0100 From: blecoq Subject: Re: COZY: Fuel Resistant Foams GeneKnapp2 wrote: > Question > > Does anyone know if PVC (H-45) is fuel resistant? > > I have been told that polyurethane foam does not hold up well in service. > > Anyone know about these two Questions or have been testing them in fuel > for any length of time? I have put 3 pieces of foam in a bottle withe fuel in it. On of the pieces is styrofoam ( the blue one used for hot wiring ), an other one is PVC , the last one is a piece of urethane ( the one used in big blocks like for the nose of the airplane and for the fittings between strakes and wing ). The blue one disappeared in the following minute. The 2 other one are still there in the bottle no change ( That experiment was done 3 years ago and I kept the bottle in my work shop untill now ). I E do not use the blue foam around the tanks. Regards Benoit LECOQ Date: Tue, 03 Mar 1998 06:00:45 +0200 From: Rego Burger Subject: COZY: Fuel Resistant Foams PVC is rated the best as far as chemical resistance is concerned. Polyurathane is also farely good. Polystyrene is no good. This is the general rule of thumb. Rego Burger, web site: http://home.intekom.com/glen/rnb.htm (home e-mail) mailto:rnb@intekom.co.za RSA Date: Tue, 03 Mar 1998 20:47:18 -0500 From: "Jeff S. Russell http://www.AeroCad.com" Subject: Re: COZY: Fuel Resistant Foams Eric Westland wrote: > It's been a year now and they all are just fine. There has been no weight > loss (epoxy dissolved away) and the foam appears to be just fine. If > anything, there has been a slight (<1%) weight gain on the mogas samples. > Since I have not changed the fuel itself except once, a light varnish-type > coating may be adding the slight weight, although I can't see one. I'd be > interested in anyone's ideas on how to improve my testing. Eric, did the clark foam seem to soak any fuel at the edges on the foam? The PVC I have soaked did not creap but the urethane did. -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com P.O. Box 7307 Port St. Lucie FL. 34985 Shop# 561-460-8020 Home# 561-343-7366 Composite workshop info: http://www.Sportair.com Date: Tue, 03 Mar 1998 21:00:10 -0800 From: Eric Westland Subject: Re: COZY: Fuel Resistant Foams Jeff S. Russell http://www.AeroCad.com wrote: > Eric, did the clark foam seem to soak any fuel at the edges on the foam? > The PVC I have soaked did not creap but the urethane did. I don't think so, but that has not been the focus of my attention. The only reason I included the turtle back samples (w/Clark substitute foam cores) with the others in fuel to begin with was that they had 2427 layups on top of them (they were window cut out pieces) and I wanted to see what the glass layups would do. After all, I only have the plans-specified PVC foam in contact with fuel in the strakes. Even then, the only place PVC foam edges are exposed to the fuel is where cut-outs were made in the baffles for draining. Where there was an ever-so-slight weight gain, I figured that some fuel may have seeped into "torn air bubbles" at the edge of the foam. Fuel would have the chance to seep in over months, but probably not drain or evaporate back out over the day or so that I would have the samples out for weighing. It's a theory, but the change is so small that I'm not at all concerned with the compatibility of fuel and the foam which has been in use for years in various canards. I hope this answers your question. As for the 2427, if anyone does have any first-hand experience with it having adverse reactions with fuel, I would hope they would bring it to this forum where those much more capable than myself could analyze it. It's not that I could not be wrong (just ask Mrs. Westland), but several of us have been testing this stuff in our own way for over a year and it always appears to be just as good with fuel as the other approved epoxies. -eric. From: "norm" Subject: Re: COZY: bad experience with foam-in-a-can Date: Fri, 5 Jun 1998 22:36:11 -0400 most of the foam in a can's use solvents, polystyrene foam is desolved by some solvents, the best way is to do it per the manual, but if you have to you can use some spray contact adhesives (make sure they are safe for the type of foam you are using). norm & monda cozy IV #202 -----Original Message----- From: Kent Ashton To: Nat Puffer Cc: cozy_builders Date: Friday, June 05, 1998 8:51 PM Subject: COZY: bad experience with foam-in-a-can >I know a few guys are using foam-in-a-can ("Great Stuff" is one brand) >to piece together foam scraps for a big piece which can be hot-wired. > I used such a piece, cut on an angle so the seam was rather wide, to >fill the fuselage gap on my canard. It was fiberglassed, filled and >sanded smooth but after I painted it and put it out in the sun, the seam >pulled in enough to see a noticeable depression in the previous smooth >surface. > It could have been due to some shrinkage in the foam seam but I'm >puzzled how that would have pulled in a relatively rigid fiberglass >surface. > >Kent A. > Date: Mon, 08 Jun 1998 12:58:29 -0800 From: hrogers@slac.stanford.edu (Howard Rogers) Subject: Re: COZY: bad experience with foam-in-a-can >I know a few guys are using foam-in-a-can ("Great Stuff" is one brand) >to piece together foam scraps for a big piece which can be hot-wired. > I used such a piece, cut on an angle so the seam was rather wide, to >fill the fuselage gap on my canard. It was fiberglassed, filled and >sanded smooth but after I painted it and put it out in the sun, the seam >pulled in enough to see a noticeable depression in the previous smooth >surface. > It could have been due to some shrinkage in the foam seam but I'm >puzzled how that would have pulled in a relatively rigid fiberglass >surface. > >Kent A. I am just a bit horrified by what I am reading here. Perhaps it is time for everyone to go back to the green pages (education section) of their plans and read up on hotwire techniques. It states most clearly there, that polystyrene is the ONLY foam you should hotwire. I further states, quite clearly, that hotwireing urethane foam is forbidden, as it produces very toxic gasses. Foam in a can is URETHANE foam. Every argument for this type of use is moot, in my opinion. --Howard Rogers, 650-926-4052 hrogers@slac.stanford.edu From: cdenk@ix.netcom.com Date: Mon, 8 Jun 1998 16:15:56 -0500 (CDT) Subject: Re: COZY: bad experience with foam-in-a-can Also pourfoam (2 part urethane) expands with heat. Look at a stiffener on the aft of my top cowl. it is bulged outward a bit. Will have to fix it one of these days. Date: Mon, 08 Jun 1998 21:26:32 -0500 From: Kent Ashton Subject: Re: COZY: bad experience with foam-in-a-can Howard Rogers wrote: > Foam in a can is URETHANE foam. Every argument for > this type of use is moot, in my opinion. It's handy sometimes to be able to patch together some foam scraps with foam-in-a-can to make a mold or something that can be hot-wired. I used a bunch of pieces to make some wheel pant molds and hot-wired them in two dimensions to get the shape I wanted. I didn't notice any noxious gases coming out of that experiment. Hey, the whole process of building a composite airplane is not for those who are weak of liver. Kent A. From: cdenk@ix.netcom.com Date: Mon, 8 Jun 1998 21:38:42 -0500 (CDT) Subject: Re: COZY: bad experience with foam-in-a-can I though the noxious gas given off by hot urethane was phosgene or something similar, but I have to admit that I have hot wired it with much ventilation, and then only small amounts. Date: Tue, 09 Jun 1998 12:20:49 -0800 From: hrogers@slac.stanford.edu (Howard Rogers) Subject: Re: COZY: bad experience with foam-in-a-can >Howard Rogers wrote: > >> Foam in a can is URETHANE foam. Every argument for >> this type of use is moot, in my opinion. > > It's handy sometimes to be able to patch together some foam scraps with >foam-in-a-can to make a mold or something that can be hot-wired. I used >a bunch of pieces to make some wheel pant molds and hot-wired them in >two dimensions to get the shape I wanted. > I didn't notice any noxious gases coming out of that experiment. Hey, >the whole process of building a composite airplane is not for those who >are weak of liver. > >Kent A. Kent, You can make light of this, if you like, but there is nothing remotely funny about Phosgene gas. I think it is a serious mistake to even suggest that this is an acceptable practice. One problem with our society's labeling of hazards is that we all become somewhat numb to the warnings, and we tend to "lump them together" and subconciously consider them somewhat equal. From there, it isn't much of a leap to ignore those that inconvenience us. The real challenge to our human nature is to maintain vigilance, and at least sort out the real big hazards from the nusciance hazards. Not many people would put a swig of cyanide in the same class with a "carcinogenic" barbequed steak, for example, and that's the type of diferentiation I am referring to, here. Phosgene is in a class with the swig of cyanide. No amount of convenience can justify ANY level of exposure to it. Yes, it might hurt you a little at a time, over many small exposures, but the real possibility exists that it could KILL you with just ONE exposure. --Howard Rogers, 650-926-4052 hrogers@slac.stanford.edu Date: Thu, 05 Nov 1998 19:37:40 -0500 From: Bulent Aliev Subject: Re: COZY: Joining foam cores I did the same thing. 3M spray glue #77 is the only one I found that has no acetone in it and will not disolve the blue foam. Bulent Bill Theeringer wrote: > John Cannon et al; > > When I made my wings (around 1985) I joined the foam blocks with 3M Super > 77 Spray Adhesive. A 7 oz. can was $6.89, I still have it! The stuff is > similar to contact cement with the convenience of a spray can. This was > not something I undertook because it seemed like a neat idea! Mike said it > was absolutely ok to do but to do it right. Thin coat, let it dry for a > few minutes then stick together. You get one try as it sticks quite well. > Hot wire cuts with no seam noticed. No effect on the foam as I tried a > sample first. I know this is one of those "but he said it was o.k." things > but it really happened. Anybody else out there do this? > > Bill Theeringer > N29EZ > In the process of boat tailing the bottom cowl.