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Polyester or Epoxy?
Hi. I'll probably get some thoughts on this. I built a 20' Osprey Triple
kayak using epoxy resin. Nice boat. Now I'm building an 18' Trident Power Cat ( johnsboatstuff.com ). He's recommending epoxy for structural work and polyester (either orthothalic or the other one, I can't remember right now, would have to look at my plans) for glassing up. Anyway it's the "better" polyester. I like the price of the polyester, but.................. Anybody have any thoughts on why I should go all epoxy or use the epoxy/polyester combo??? Thanks for any comments, thoughts. Amateur 2nd boat builder in the Great White Frozen North, Allan |
Polyester or Epoxy?
In article ,
"Allan" wrote: Hi. I'll probably get some thoughts on this. I built a 20' Osprey Triple kayak using epoxy resin. Nice boat. Now I'm building an 18' Trident Power Cat ( johnsboatstuff.com ). He's recommending epoxy for structural work and polyester (either orthothalic or the other one, I can't remember right now, would have to look at my plans) for glassing up. Anyway it's the "better" polyester. I like the price of the polyester, but.................. Anybody have any thoughts on why I should go all epoxy or use the epoxy/polyester combo??? Thanks for any comments, thoughts. Amateur 2nd boat builder in the Great White Frozen North, Allan build in epoxy - period. polyester has no secondary bond strength and not a lot of primary bond strength. epoxy is not that much more expensive and could well save your boat. epoxy actually sticks to the glass where polyester does not; it merely hardens *around* the glass fibers. that's why a polyester laminate peels apart along the surface of the reinforcement when it goes into failure. -mo |
Polyester or Epoxy?
experience varies. on some surfaces polyester is fine. some builders have
been using is successfully for decades. but as there is no experimental data a lot of builders pay extra and use epoxy. if your designer recommends polyester you might want to contact him or her to find out what feedback he is getting from builders. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
Allan,
Thirty five years ago, when epoxy was hundreds of dollars a gallon, we used poly for glassing, never as an adhesive (it was not as strong as a good glue). The general consensus of the experts was that It should only be used for glassing on a virgin, stable, substrate which was mostly plywood back then. NEVER on planking, strips, etc or previously painted wood, because the bonding strength and sheer strength would not hold up to the forces which resulted in the expansion of these substrates or the poor penetration of the previously painted surface. The first coat of poly was thinned with styrene (the base solvent of polyester) 30% as I recall, immediately followed by a straight coat that the glass was laid into. The rest of the buildup was as with epoxy except you had to work your ass off if the job was of any size. This method worked ok and some of it lasted at least several decades. The ones that failed were usually the ones that violated the rules above or were boats that were grossly mistreated. For instance, acetone was substituted for styrene which reduced the mechanicals of the poly by about 20% to 30% as I recall. About the same time I was introduced to epoxy in the lab at GE (they could afford it). For the next twenty or so years I waited for the price of epoxy to come down to my recreational budget level. That was about 15 years ago and I have not used poly since. As far as I am concerned, the only justification for poly is in high volume production molded parts (unfortunately like boat hulls). But even there you will see the highest quality products using epoxy. Bottom line. With epoxy at $40 to $50 a gallon, I wouldn't use poly if it were FREE! My opinion, worth what you paid for it. Regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. |
Polyester or Epoxy?
As one who has need for some poly glassing I have often thought there should
be another news group for "ordinary" people. My whole boat is poly so why do some alterations in epoxy? BruceM "Terry Spragg" wrote in message ... Michael O'Dell wrote: In article , "Allan" wrote: Hi. I'll probably get some thoughts on this. I built a 20' Osprey Triple kayak using epoxy resin. Nice boat. Now I'm building an 18' Trident Power Cat ( johnsboatstuff.com ). He's recommending epoxy for structural work and polyester (either orthothalic or the other one, I can't remember right now, would have to look at my plans) for glassing up. Anyway it's the "better" polyester. I like the price of the polyester, but.................. Anybody have any thoughts on why I should go all epoxy or use the epoxy/polyester combo??? Thanks for any comments, thoughts. Amateur 2nd boat builder in the Great White Frozen North, Allan build in epoxy - period. polyester has no secondary bond strength and not a lot of primary bond strength. epoxy is not that much more expensive and could well save your boat. epoxy actually sticks to the glass where polyester does not; it merely hardens *around* the glass fibers. that's why a polyester laminate peels apart along the surface of the reinforcement when it goes into failure. -mo I guess that's why all my 30 year old poly boats just collapsed into piles of hairy dust in my backyard, eh? Zero strength, eh? How do you calculate the cost benefit from this supposed longer life for epoxy, given that the life span is still generally indeterminate for both types under reasonable stresses? I have heard of very few poly boats disintegrating in any remarkably shorter time than epoxy, even in contests involving rocks and stuff. Such extremeist statements suggest you must be a berserker stock market manipulator with interests and positions in the epoxy chemicals market bordering so extremely on the insane as to suggest you sell epoxy mainly to be able to continue to dispose of toxic chemicals added in small amounts to the resins, just like some shampoo vendors I suspected of doing just that until your arguement was so strongly stated and foolishly revealed ;-) Now, as far as skin irritation and developed allergies and consequent lifetime sensitivities and costs associated with respirators, deformed babies, etc, I would favour poly quite strongly for a hobby builder, especially a relatively inexperienced one, especially for a first build. Commercially, the evidence is overwhelming. I cannot imagine anyone smart enough to be able to afford the costs of epoxy being insensitive to those cost benefit analyses so evidently performed and adhered to by professional builders. You just try to get an informed professional to build in epoxy and then count the costs. -- Terry K - My email address is MY PROPERTY, and is protected by copyright legislation. Permission to reproduce it is specifically denied for mass mailing and unrequested solicitations. Spamspoof salad by spamchock TM - SofDevCo ® |
Polyester or Epoxy?
BruceM wrote:
As one who has need for some poly glassing I have often thought there should be another news group for "ordinary" people. My whole boat is poly so why do some alterations in epoxy? And be chained to epoxy therever after? When I moved the head intake aboard my "The Penny Louise" HR28 sloop to make room for monkey feet under the new saloon booth table decoratif, I used a one piece 3/8" solid plug of poly glass tapered to fit the ground out hole, pressed between thin plywoods lined with waxed paper. It never even needed sanding after it cured. After vandals burned my boat, while the insurance swindler was viewing the wreckage, I bashed in the speedo sensor to allow the water to drain. We came back after a few beers so he could check out the remains of the hull interior (?) I paid for the lunch. It seems to me now that I could have tried to bash in the 3 year old patch, but I didn't think of it then. After this long, I think that the cradle, hull, engine, gas fuel tank, boom, ballast, shaft and rudder were useable, (I had just re-glassed the shaft log using epoxy), I just didn't have the heart to rebuild. After a year of arguing with Parizeau et bureau legal d'assurance, I accepted 14,500 and carriage for a boat that was insured and not replaceable for 18,500, it's purchase price. I maintain perfect faith that it would have been one hell of a job to bash in that plug. Wanna buy a 2 cylinder, 2 cycle gas 20 hp Lloyds Mariner (German) inboard with electric start, reverser, shaft and prop? It did well on the 'penile ooies', as we called her. Terry K BruceM "Terry Spragg" wrote in message ... Michael O'Dell wrote: In article , "Allan" wrote: Hi. I'll probably get some thoughts on this. I built a 20' Osprey Triple kayak using epoxy resin. Nice boat. Now I'm building an 18' Trident Power Cat ( johnsboatstuff.com ). He's recommending epoxy for structural work and polyester (either orthothalic or the other one, I can't remember right now, would have to look at my plans) for glassing up. Anyway it's the "better" polyester. I like the price of the polyester, but.................. Anybody have any thoughts on why I should go all epoxy or use the epoxy/polyester combo??? Thanks for any comments, thoughts. Amateur 2nd boat builder in the Great White Frozen North, Allan build in epoxy - period. polyester has no secondary bond strength and not a lot of primary bond strength. epoxy is not that much more expensive and could well save your boat. epoxy actually sticks to the glass where polyester does not; it merely hardens *around* the glass fibers. that's why a polyester laminate peels apart along the surface of the reinforcement when it goes into failure. -mo I guess that's why all my 30 year old poly boats just collapsed into piles of hairy dust in my backyard, eh? Zero strength, eh? How do you calculate the cost benefit from this supposed longer life for epoxy, given that the life span is still generally indeterminate for both types under reasonable stresses? I have heard of very few poly boats disintegrating in any remarkably shorter time than epoxy, even in contests involving rocks and stuff. Such extremeist statements suggest you must be a berserker stock market manipulator with interests and positions in the epoxy chemicals market bordering so extremely on the insane as to suggest you sell epoxy mainly to be able to continue to dispose of toxic chemicals added in small amounts to the resins, just like some shampoo vendors I suspected of doing just that until your arguement was so strongly stated and foolishly revealed ;-) Now, as far as skin irritation and developed allergies and consequent lifetime sensitivities and costs associated with respirators, deformed babies, etc, I would favour poly quite strongly for a hobby builder, especially a relatively inexperienced one, especially for a first build. Commercially, the evidence is overwhelming. I cannot imagine anyone smart enough to be able to afford the costs of epoxy being insensitive to those cost benefit analyses so evidently performed and adhered to by professional builders. You just try to get an informed professional to build in epoxy and then count the costs. -- Terry K - My email address is MY PROPERTY, and is protected by copyright legislation. Permission to reproduce it is specifically denied for mass mailing and unrequested solicitations. Spamspoof salad by spamchock TM - SofDevCo ® -- Terry K - My email address is MY PROPERTY, and is protected by copyright legislation. Permission to reproduce it is specifically denied for mass mailing and unrequested solicitations. Spamspoof salad by spamchock TM - SofDevCo ® |
Polyester or Epoxy?
Terry Spragg wrote:
I guess that's why all my 30 year old poly boats just collapsed into piles of hairy dust in my backyard, eh? Zero strength, eh? How do you calculate the cost benefit from this supposed longer life for epoxy, given that the life span is still generally indeterminate for both types under reasonable stresses? I have heard of very few poly boats disintegrating in any remarkably shorter time than epoxy, even in contests involving rocks and stuff. Such extremeist statements suggest you must be a berserker stock market manipulator with interests and positions in the epoxy chemicals market bordering so extremely on the insane as to suggest you sell epoxy mainly to be able to continue to dispose of toxic chemicals added in small amounts to the resins, just like some shampoo vendors I suspected of doing just that until your arguement was so strongly stated and foolishly revealed ;-) Now, as far as skin irritation and developed allergies and consequent lifetime sensitivities and costs associated with respirators, deformed babies, etc, I would favour poly quite strongly for a hobby builder, especially a relatively inexperienced one, especially for a first build. Commercially, the evidence is overwhelming. I cannot imagine anyone smart enough to be able to afford the costs of epoxy being insensitive to those cost benefit analyses so evidently performed and adhered to by professional builders. You just try to get an informed professional to build in epoxy and then count the costs. Wow! Sounds like some Canuck eco-wacko failed to get his rabies shot when it was due. Doesn't spell too well, either: extremEist; berserkER; arguEment; there must be a surplus of Es and Rs up there in the frozen north, EH? |
Polyester or Epoxy?
BruceM wrote:
As one who has need for some poly glassing I have often thought there should be another news group for "ordinary" people. My whole boat is poly so why do some alterations in epoxy? BruceM So they will stick together? Just a thought. |
Polyester or Epoxy?
Edward Greeley wrote:
Terry Spragg wrote: I guess that's why all my 30 year old poly boats just collapsed into piles of hairy dust in my backyard, eh? Zero strength, eh? How do you calculate the cost benefit from this supposed longer life for epoxy, given that the life span is still generally indeterminate for both types under reasonable stresses? I have heard of very few poly boats disintegrating in any remarkably shorter time than epoxy, even in contests involving rocks and stuff. Such extremeist statements suggest you must be a berserker stock market manipulator with interests and positions in the epoxy chemicals market bordering so extremely on the insane as to suggest you sell epoxy mainly to be able to continue to dispose of toxic chemicals added in small amounts to the resins, just like some shampoo vendors I suspected of doing just that until your arguement was so strongly stated and foolishly revealed ;-) Now, as far as skin irritation and developed allergies and consequent lifetime sensitivities and costs associated with respirators, deformed babies, etc, I would favour poly quite strongly for a hobby builder, especially a relatively inexperienced one, especially for a first build. Commercially, the evidence is overwhelming. I cannot imagine anyone smart enough to be able to afford the costs of epoxy being insensitive to those cost benefit analyses so evidently performed and adhered to by professional builders. You just try to get an informed professional to build in epoxy and then count the costs. Wow! Sounds like some Canuck eco-wacko failed to get his rabies shot when it was due. Doesn't spell too well, either: extremEist; berserkER; arguEment; there must be a surplus of Es and Rs up there in the frozen north, EH? Well, just to indulge a whim before bedtime... I got a flu shot, essentially for free, here in N.B. Canada after a 20 minute wait at my local clinique. It was so cold, they shot it into my arm with a bb gun. If I was hugging a tree, it would only be to have a grip on it sufficiently firm that I could expedite it's insertion into one of your useless orifices. Or, I could wait quite a while until the right one becomes available for expansive exploratory applications. Any topical applications you might suggest? The last resort of frustrated non sequitorialist rambler bitche usegroup pussies is to attack spalling, using axe mini spool chequers is ewe kin git widow pain fur 'em, or your baby sister's ass. d'UuhH? Spell check that, Quixote fan. Do your Freudian slops, like your mother? I mean, what's your OT point? Just read over your post, and reflect on how petty seems your pseudo-intellectual questing to jot a tittle or two. Capice? If you don't feel insulted, you should get behind that. Or, maybe this response was the best compliment you ever got, or will get? Nobody cares. Contribute, or leech. -- Terry K - My email address is MY PROPERTY, and is protected by copyright legislation. Permission to reproduce it is specifically denied for mass mailing and unrequested solicitations. Spamspoof salad by spamchock TM - SofDevCo ® |
Polyester or Epoxy?
For more than twenty years, we did almost all the fiberglass work that
we did with one or the other kinds of polyester and then a little bit of vinylester. These were the industries lead materials. Epoxy was reserved for high temperature and polystrene foam assemblies largely because of cost. In that time I did experience several dozen mix failures (where the pot kicks too soon or does not harden correctly) and all mixing was done on a balance - no by guess and by gosh. Also, while working with polyester, we (my father and I ran the boat shop) had numerous bond failures in the work we had done. We also repaired a significant number of bond failures in other people's work - four that I remember were factory jobs. Two of those factory jobs were conversions to wheel steer that lost cable turning point anchors. Shortly before my father died in 1980, we started to change to epoxy. This was mostly driven by the little pumps that could be used measure the material for mixing. We soon discovered that, except for large builds where material was a big part of the overall cost, the epoxy jobs were at least no more expensive because of the lack of lost material. I have one mix failure (caused by a helper that did not understand the mix ratio was 1 pump stroke to 1 pump stroke), and have never been able to identify a bond failure in my own work. We now do all or clean up with white vinegar and reserve acetone and MEK for work outside. Matt Colie www.southpointechandler.com BruceM wrote: As one who has need for some poly glassing I have often thought there should be another news group for "ordinary" people. My whole boat is poly so why do some alterations in epoxy? BruceM "Terry Spragg" wrote in message ... Michael O'Dell wrote: In article , "Allan" wrote: Hi. I'll probably get some thoughts on this. I built a 20' Osprey Triple kayak using epoxy resin. Nice boat. Now I'm building an 18' Trident Power Cat ( johnsboatstuff.com ). He's recommending epoxy for structural work and polyester (either orthothalic or the other one, I can't remember right now, would have to look at my plans) for glassing up. Anyway it's the "better" polyester. I like the price of the polyester, but.................. Anybody have any thoughts on why I should go all epoxy or use the epoxy/polyester combo??? Thanks for any comments, thoughts. Amateur 2nd boat builder in the Great White Frozen North, Allan build in epoxy - period. polyester has no secondary bond strength and not a lot of primary bond strength. epoxy is not that much more expensive and could well save your boat. epoxy actually sticks to the glass where polyester does not; it merely hardens *around* the glass fibers. that's why a polyester laminate peels apart along the surface of the reinforcement when it goes into failure. -mo I guess that's why all my 30 year old poly boats just collapsed into piles of hairy dust in my backyard, eh? Zero strength, eh? How do you calculate the cost benefit from this supposed longer life for epoxy, given that the life span is still generally indeterminate for both types under reasonable stresses? I have heard of very few poly boats disintegrating in any remarkably shorter time than epoxy, even in contests involving rocks and stuff. Such extremeist statements suggest you must be a berserker stock market manipulator with interests and positions in the epoxy chemicals market bordering so extremely on the insane as to suggest you sell epoxy mainly to be able to continue to dispose of toxic chemicals added in small amounts to the resins, just like some shampoo vendors I suspected of doing just that until your arguement was so strongly stated and foolishly revealed ;-) Now, as far as skin irritation and developed allergies and consequent lifetime sensitivities and costs associated with respirators, deformed babies, etc, I would favour poly quite strongly for a hobby builder, especially a relatively inexperienced one, especially for a first build. Commercially, the evidence is overwhelming. I cannot imagine anyone smart enough to be able to afford the costs of epoxy being insensitive to those cost benefit analyses so evidently performed and adhered to by professional builders. You just try to get an informed professional to build in epoxy and then count the costs. -- Terry K - My email address is MY PROPERTY, and is protected by copyright legislation. Permission to reproduce it is specifically denied for mass mailing and unrequested solicitations. Spamspoof salad by spamchock TM - SofDevCo ® |
Polyester or Epoxy?
"BruceM" wrote in message ...
As one who has need for some poly glassing I have often thought there should be another news group for "ordinary" people. My whole boat is poly so why do some alterations in epoxy? BruceM No reason at all! But I still say for new construction, epoxy is just easier to use, guess I am just lazy and want the boat to come out right the first time without the unaviodable waste of material, sanding off early cured material, scraping off material that did not "like" the ambient temp, humidity, or mixing ratio you have chosen to address the same. I did build several boats in poly in the beginning, when I finally broke down and used epoxy, it was a life altering experience, kinda like going from a tricycle to a Porche... "Terry Spragg" wrote in message ... Michael O'Dell wrote: In article , "Allan" wrote: Hi. I'll probably get some thoughts on this. I built a 20' Osprey Triple kayak using epoxy resin. Nice boat. Now I'm building an 18' Trident Power Cat ( johnsboatstuff.com ). He's recommending epoxy for structural work and polyester (either orthothalic or the other one, I can't remember right now, would have to look at my plans) for glassing up. Anyway it's the "better" polyester. I like the price of the polyester, but.................. Anybody have any thoughts on why I should go all epoxy or use the epoxy/polyester combo??? Thanks for any comments, thoughts. Amateur 2nd boat builder in the Great White Frozen North, Allan build in epoxy - period. polyester has no secondary bond strength and not a lot of primary bond strength. epoxy is not that much more expensive and could well save your boat. epoxy actually sticks to the glass where polyester does not; it merely hardens *around* the glass fibers. that's why a polyester laminate peels apart along the surface of the reinforcement when it goes into failure. -mo I guess that's why all my 30 year old poly boats just collapsed into piles of hairy dust in my backyard, eh? Zero strength, eh? How do you calculate the cost benefit from this supposed longer life for epoxy, given that the life span is still generally indeterminate for both types under reasonable stresses? I have heard of very few poly boats disintegrating in any remarkably shorter time than epoxy, even in contests involving rocks and stuff. Such extremeist statements suggest you must be a berserker stock market manipulator with interests and positions in the epoxy chemicals market bordering so extremely on the insane as to suggest you sell epoxy mainly to be able to continue to dispose of toxic chemicals added in small amounts to the resins, just like some shampoo vendors I suspected of doing just that until your arguement was so strongly stated and foolishly revealed ;-) Now, as far as skin irritation and developed allergies and consequent lifetime sensitivities and costs associated with respirators, deformed babies, etc, I would favour poly quite strongly for a hobby builder, especially a relatively inexperienced one, especially for a first build. Commercially, the evidence is overwhelming. I cannot imagine anyone smart enough to be able to afford the costs of epoxy being insensitive to those cost benefit analyses so evidently performed and adhered to by professional builders. You just try to get an informed professional to build in epoxy and then count the costs. -- Terry K - My email address is MY PROPERTY, and is protected by copyright legislation. Permission to reproduce it is specifically denied for mass mailing and unrequested solicitations. Spamspoof salad by spamchock TM - SofDevCo ® |
Polyester or Epoxy?
Bruce,
The "ordinary" people are the ones that can best justify epoxy because the quantity they typically us is small compared to the production user. To answer your question about why to use epoxy instead of poly is, that it makes a better repair. Regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. |
Polyester or Epoxy?
|
Polyester or Epoxy?
I have had hundreds of my customers using polyester resins on my Sevtec surface
skimmer hulls without difficulty, and a few using epoxy, against my advice, with difficulty. In one case, amine blush of the epoxy caused the failure of tabbing that held some hull panels together and the result of using a brake, Yes, a brake on a surface skimmer, at about 35mph, caused the hull bottom to peel off, fortunately with no significant injuries, even though one person of three aboard went through the hole in the bottom and came up treading water behind the craft. Epoxy is very critical in mix ratio, and that is why scales or proportional pumps are used, while polyester catalysis is easily done with a small graduate cylinder, and variations of mix ratio of 20%, which would certainly spell disaster with epoxy, are of no concern with polyester. Some structures do benefit from epoxy, but if the structure strength or stiffness is governed by the glass, not the resin, epoxy may be a waste, except in long term exposure to warm climate salt water. Subject: Polyester or Epoxy? From: (Backyard Renegade) Date: Thu, Jan 15, 2004 3:00 PM Message-id: (Ron Thornton) wrote in message ... Bruce, The "ordinary" people are the ones that can best justify epoxy because the quantity they typically us is small compared to the production user. To answer your question about why to use epoxy instead of poly is, that it makes a better repair. Regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. But that is really not even much of a factor anymore. To build a 12 foot skiff with flotation and proper materials, it is going to cost you $250.00 on materials and hardware alone (assuming exterior plywood hull), and just for ha ha's, say $25 for a set of plans. If you use poly instead of epoxy, you might save $25 to $30 bucks max on the whole build and more times than not, I have seen first time builders end up using 2-3 times more poly than the plan would call for. The learning curve for mixing poly is treacherous, (bring a good scale and a calculator too) especially to the home builder that may be building outdoors, or in a non conditioned barn, tent, etc. Let me take a minute for anyone who is not clear about mixing the two products. With polyester, you must first calculate your catalyst ratio. So many ounces of resin, to so many drops of catalyst. This mixture is not only very delicate, but it changes depending on ambient temp, humidity, how fast you want things to cure and the required differences in the catalyst mixtures is very minute, and are based on the starting formula plus the users best guess or experience of how to alter that formula to suit the conditions at the time. Any very slight miscalculation in the mix or even how many clouds will pass over during the application can cause total havoc resulting in a slimy hot slop all over your boat that is extremely difficult to remove (think half hardened plastic mixed with cold roofing tar), that is to hard to scrape, and to soft to sand, or a fast kick which catches you with only half of your glass saturated, or just gobs up thicker and thicker as you try to catch up and save something. In both cases the only solution is a lot of elbow grease and lot's of wasted time and sand paper, scrapers, and then a re-application. With Epoxy, the cure rate is also dependant on the temp and humidity of the work area, but not nearly as fast or as radical. Mixing is done with calibrated pumps, something like one pump of resin to one pump of hardener. If you want a faster cure, substitute a "fast" hardener, if slower is your style or a bigger area to do in warmer weather, use a slower hardener, no calculators, no precision scales, no guesswork at all. If your pumps are working properly, and you don't get lazy mixing, even mistakes will harden nicely to be ground or sanded off. One extreme case (admittedly the most extreme I am aware of) was a couple of years ago when I came in very late by e-mail on a build of "Diablo", a 15 foot Bolger type skiff. The plan calls for 2 1/2 gallons of resin. This guy had a terrible summer of heat and cold, never really got the mixtures down in his one build. He spent literally dozens of hours scraping and sanding and just throwing out resin that either kicked to fast, or not at all. He ended up using 11 gallons of poly on the build at a total cost of over $200 for resin alone. Not to mention lost thickeners, thinners, brushes, sand paper, scrapers, time, time, time, time, time... I will stop now, but he has since built another boat, but this time he used epoxy, no problems. Now I don't expect any first timer to build Diablo with 2 1/2 gallons of resin, but certainly 3-3 1/2 should be the max. One final comment. I do not know what the original poster should do, I have no experience there, I don't do restores ;-) I also do realize that poly has it's place in composite shops where big lay-up is done or for molded parts, but somehow this thread seemed to get hijacked to my area so I thought I would chime in here. So this has been my advice, take if for what you paid. Scotty from SmallBoats.com BRBR Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A |
Polyester or Epoxy?
Backyard Renegade ) writes:
Let me take a minute for anyone who is not clear about mixing the two products. Epoxy is risky to work with because the proportions have to be exact and the mix has to be thorough. If it isn't done correctly the mistake cannot be corrected once is it on the hull. Polyester proportions do not have to be as exact or the mixing as thorough. If the polyester doesn't cure on the hull you can brush on more catalyst. I have spread uncatalysed resin onto a small plywood hull and let it soak into the wood for 24 hours before brushing on second catalysed coat. After allowing another 24 (acutally 18) hours to cure it was thorougly cured with a good bond into the wood. Uncatalysed polyester thickened with whatever can be used for filleting which allows unlimited time to shape and smooth the fillets. Then fibreglass cloth soaked in catalysed resin can be put over the fillet and the whole thing will cure. In my opinion polyester is both easier and safer to work with. For some reason the last polyester I bought doesn't even smell as it cures. It may be an environmental thing. In some jurisdictions licenced boatbuilders are not allowed to let gases from curing resins escape into the atmosphere which has lead to fans and filters being installed and to a technique which looks like a dry vacuum bagging setup with injected resin. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
William,
If what you say in true, why not soak all the laminating schedule in uncatalysed resin lay it up and then spray or brush on a light coat of catalyst? The manufacture's published mix ratio's do not seem to be all that open. If proximity to catalyst is enough the get the polyester material to cure, then how is it that I have found uncured resin imbeded in structures a decade or more after the build date? Back when we used polyester exclusively, never-cure mixes did seem to a real possibility as well as the heat up while mixing version. In our shops we have done eperiments with the procedures you have outlined and did not have the success that you seen to have had. Infact we were able to show some remarkable failures on test assemblies. Matt Colie www.southpointechandler.com William R. Watt wrote: Backyard Renegade ) writes: Let me take a minute for anyone who is not clear about mixing the two products. Epoxy is risky to work with because the proportions have to be exact and the mix has to be thorough. If it isn't done correctly the mistake cannot be corrected once is it on the hull. Polyester proportions do not have to be as exact or the mixing as thorough. If the polyester doesn't cure on the hull you can brush on more catalyst. I have spread uncatalysed resin onto a small plywood hull and let it soak into the wood for 24 hours before brushing on second catalysed coat. After allowing another 24 (acutally 18) hours to cure it was thorougly cured with a good bond into the wood. Uncatalysed polyester thickened with whatever can be used for filleting which allows unlimited time to shape and smooth the fillets. Then fibreglass cloth soaked in catalysed resin can be put over the fillet and the whole thing will cure. In my opinion polyester is both easier and safer to work with. For some reason the last polyester I bought doesn't even smell as it cures. It may be an environmental thing. In some jurisdictions licenced boatbuilders are not allowed to let gases from curing resins escape into the atmosphere which has lead to fans and filters being installed and to a technique which looks like a dry vacuum bagging setup with injected resin. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
"William R. Watt" wrote in message
... Epoxy is risky to work with because the proportions have to be exact and the mix has to be thorough. Pleeeze guys, can someone explain to me what is so difficult about givin the resin pump and the hardener pump an equal number of pushes and stirring a mixture firmly for two minutes???? If one cannot perform such a simple task, I think building a complete boat is out of the question....... Meindert |
Polyester or Epoxy?
Matt Colie ) writes:
In our shops we have done eperiments with the procedures you have outlined and did not have the success that you seen to have had. Infact we were able to show some remarkable failures on test assemblies. Jaques Mertens wrote much the same in an earlier thread on this never-ending topic. From the sound of it you are both working on big boats with large cross sectional areas, eg solid keels, which may explain the differences. I've only built small plywood boats I can pick up and put on top of the car, under 50 lb. TF Jones describes using uncatalysed thickened poylester resin for filleting on a Dobler 16 made out of polyester/fibreglass panels substituted for the usual plywood panels. The design being discussed in this thread is also small. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
"Meindert Sprang" ) writes:
Pleeeze guys, can someone explain to me what is so difficult about givin the resin pump and the hardener pump an equal number of pushes and stirring a mixture firmly for two minutes???? If one cannot perform such a simple task, I think building a complete boat is out of the question....... I tried buying a small quantity of epoxy packaged in twin pumps and had all sorts of difficulty with it. It never worked smoothly. It was messy. A lot was wasted. For the small jobs I use epoxy for I only buy it in the twin squeeze tubes now. I find it a lot easier counting drops of polyester catalyst than trying to measure out equal volumes of epoxy resin and hardener. Only one container is used for measuring with polyester. Overall easier to work with in my opinion. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
"William R. Watt"writes: I tried buying a small quantity of epoxy packaged in twin pumps and had all sorts of difficulty with it. It never worked smoothly. It was messy. A lot was wasted. For the small jobs I use epoxy for I only buy it in the twin squeeze tubes now. snip Stop by your handy dandy restaurant supply house and buy some plastic and/or paper cups. I use, 1 oz, 2 oz & 4 oz to mix small quantities of epoxy. It's simply NBD. -- Lew S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland) Visit: http://home.earthlink.net/~lewhodgett for Pictures |
Polyester or Epoxy?
I would be real interested inknowing how you would apply 1/4 oz of MEKP
to 6 or 8 square feet of cloth. ;-) I use polyester for molds and things like shower basins and grey water tanks but compared to epoxy it is a PITA. A quart of resin requires something between 5 to 10 ml of MEKP depending on the temperature, the hunidity and the phase of the moon. A ml to much and it turns to gum before you can get the glass laid tight. If you don't mix it extremely well it forms jelly beans in the pot. If you are an ounce short you still have to mix a pint because it is almost impossible to measure that small amount of MEKP. With epoxy you just get a squirt of resin and a squirt of hardner and you have about half an ounce. If it is hot you use a slow hardner. If it is nice out you use a normal harnder. If it is cold you use a fast hardner. But it is always a squirt of each. IF you need a lot the hardware store sell graduated mixing pots for about $.75 that are good for several sessions. IF you don't glas very often, epoxy has a shelf life measured in years. I have never had a can of polyester make it past 9 months after it is opened. William R. Watt wrote: Backyard Renegade ) writes: Let me take a minute for anyone who is not clear about mixing the two products. Epoxy is risky to work with because the proportions have to be exact and the mix has to be thorough. If it isn't done correctly the mistake cannot be corrected once is it on the hull. Polyester proportions do not have to be as exact or the mixing as thorough. If the polyester doesn't cure on the hull you can brush on more catalyst. I have spread uncatalysed resin onto a small plywood hull and let it soak into the wood for 24 hours before brushing on second catalysed coat. After allowing another 24 (acutally 18) hours to cure it was thorougly cured with a good bond into the wood. Uncatalysed polyester thickened with whatever can be used for filleting which allows unlimited time to shape and smooth the fillets. Then fibreglass cloth soaked in catalysed resin can be put over the fillet and the whole thing will cure. In my opinion polyester is both easier and safer to work with. For some reason the last polyester I bought doesn't even smell as it cures. It may be an environmental thing. In some jurisdictions licenced boatbuilders are not allowed to let gases from curing resins escape into the atmosphere which has lead to fans and filters being installed and to a technique which looks like a dry vacuum bagging setup with injected resin. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
Polyester or Epoxy?
Glenn Ashmore wrote:
I would be real interested inknowing how you would apply 1/4 oz of MEKP to 6 or 8 square feet of cloth. ;-) I use polyester for molds and things like shower basins and grey water tanks but compared to epoxy it is a PITA. A quart of resin requires something between 5 to 10 ml of MEKP depending on the temperature, the hunidity and the phase of the moon. A ml to much and it turns to gum before you can get the glass laid tight. If you don't mix it extremely well it forms jelly beans in the pot. If you are an ounce short you still have to mix a pint because it is almost impossible to measure that small amount of MEKP. With epoxy you just get a squirt of resin and a squirt of hardner and you have about half an ounce. If it is hot you use a slow hardner. If it is nice out you use a normal harnder. If it is cold you use a fast hardner. But it is always a squirt of each. IF you need a lot the hardware store sell graduated mixing pots for about $.75 that are good for several sessions. IF you don't glas very often, epoxy has a shelf life measured in years. I have never had a can of polyester make it past 9 months after it is opened. Absolutely. I've done a bit of aircraft fiberglass work, but I've bever built a glass hull. http://home.flash.net/~lamb01/cowl.htm I use large syringes from the vet for mixing. My resin mix is 6:1 by volumn. 60cc of resin in the big shot. 10 cc of hardner in the little one. Its easy to double that with two shots of each. But that's about as much resin as I mix in one cup. For large layups, I premix 140cc in baggies and put them in the fridge. I don't mean to step on any toes, but since this is a boat building forum... West is a commonly recognized epoxy but imho West is NOT a sutable laminating resin for making fiberglass parts. It's fabulous with wood. But the mechanical properties are low and glass parts tend to be brittle. I've used Dow 330 for years, but can't get it any more. Now I mostly use AeroPoxy. There are several inexpensive laminating resins listed in Aircraft Spruce. There are some expensive resins listed too! Glassing wood? West is best. But for glass or carbon parts, there are much better resins. Richard Just my opinion, I could be wrong. |
Polyester or Epoxy?
"William R. Watt" wrote in message
... I tried buying a small quantity of epoxy packaged in twin pumps and had all sorts of difficulty with it. It never worked smoothly. It was messy. A lot was wasted. For the small jobs I use epoxy for I only buy it in the twin squeeze tubes now. I use the pump set from West. The easiest way to mix. One push on each pump and you have a smal dose of the perfect mix. I find it a lot easier counting drops of polyester catalyst than trying to measure out equal volumes of epoxy resin and hardener. Only one container is used for measuring with polyester. Overall easier to work with in my opinion. You can also mix by weight. I have used a digital scale for that. You pour, for instance, 100 grams of epoxy, followed by 20 grams of hardener. Easy. I would think that counting drops is a very unreliable method. the drop size would be very dependant on the viscosity of the calalyst, right? Meindert |
Polyester or Epoxy?
Richard Lamb wrote: I don't mean to step on any toes, but since this is a boat building forum... West is a commonly recognized epoxy but imho West is NOT a sutable laminating resin for making fiberglass parts. It's fabulous with wood. But the mechanical properties are low and glass parts tend to be brittle. I've used Dow 330 for years, but can't get it any more. Now I mostly use AeroPoxy. There are several inexpensive laminating resins listed in Aircraft Spruce. There are some expensive resins listed too! Glassing wood? West is best. But for glass or carbon parts, there are much better resins. That is correct. That is also why West has a sister line called Pro-Set which is a laminating epoxy. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
Polyester or Epoxy?
Glenn Ashmore ) writes:
I would be real interested inknowing how you would apply 1/4 oz of MEKP to 6 or 8 square feet of cloth. ;-) mixed with some resin. :) IF you don't glas very often, epoxy has a shelf life measured in years. I have never had a can of polyester make it past 9 months after it is opened. I had a partial one quart can of polyester resin and small tube of catalyst in the back of the 'fridge from 1981 to 2000 and it was fine. The twist off cap on the can would sieze up and had to be turned with a pair of pliers. I've started on another quart can now. From time to time I still use the small jar of white tinting resin that was with the original. I still keep it all at the back of the 'fridge. I wrap opened tubes of PL Premium polyurethane adhesive in plastic and keep that in the freezer accordign to advice posted in this newsgroup. It can be months between applications. Works fine. I let both the polyester and polyurethane warm up to room temperature before using. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
A number of years ago WEST printed a small article in their 'How To . . .'
magazine. {subscriptions are free, just call them}. It was on just this subject and included a couple of dimensioned drawings. The crux of the story/drawings was a method of employing 'stops' or 'steps' on the pump shafts. By cutting the shapes from some 1/4inch material and placing the proper 'end' between the pump 'head' and 'base', you can get a REPEATABLE '50 percent' or '25percent' pump. I used Hardboard and painted them each a different color and marked them. With the a 'full pump' discharging approximately 1 ounce of 'mix', I have the ability to also get 1/2 ounce and 1/4 ounce {approximately} quantities for those small projects/uses. I use the 5 to 1 formulation . . . and the set-up works just as well with my 'standard' RAKA epoxy. Regards & Good Luck Ron Magen Backyard Boatshop "Meindert Sprang" wrote in message ... SNIP I use the pump set from West. The easiest way to mix. One push on each pump and you have a smal dose of the perfect mix. SNIP |
Polyester or Epoxy?
"Meindert Sprang" ) writes:
I would think that counting drops is a very unreliable method. the drop size would be very dependant on the viscosity of the calalyst, right? not so it's noticeable. one drop of catalyst for every 1/2 teaspoon of resin. the drop squeezes out of a pinhole in a plastic container with a bit of thumb pressure. works every time for me. I'd be more suspect of the size of the pinhole but I've had no problems with it. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
Hi Barry
I would have to say that poor skills and bad work practice caused the failure of the tabbing , not the amine blush of the epoxy. The first BIG mistake the builder made was not following the designers specs for construction to the letter. The second stupid move was not reading the instructions for use of the product he chose to substitute or being the least bit familiar with it. I bet he made alot more mistakes too. scary -- From the rocky shores of the Skykomish river David Bosworth http://www.premier1.net/~daveb/ Barry Palmer wrote in message ... I have had hundreds of my customers using polyester resins on my Sevtec surface skimmer hulls without difficulty, and a few using epoxy, against my advice, with difficulty. In one case, amine blush of the epoxy caused the failure of tabbing that held some hull panels together and the result of using a brake, Yes, a brake on a surface skimmer, at about 35mph, caused the hull bottom to peel off, fortunately with no significant injuries, even though one person of three aboard went through the hole in the bottom and came up treading water behind the craft. Epoxy is very critical in mix ratio, and that is why scales or proportional pumps are used, while polyester catalysis is easily done with a small graduate cylinder, and variations of mix ratio of 20%, which would certainly spell disaster with epoxy, are of no concern with polyester. Some structures do benefit from epoxy, but if the structure strength or stiffness is governed by the glass, not the resin, epoxy may be a waste, except in long term exposure to warm climate salt water. Subject: Polyester or Epoxy? From: (Backyard Renegade) Date: Thu, Jan 15, 2004 3:00 PM Message-id: (Ron Thornton) wrote in message ... Bruce, The "ordinary" people are the ones that can best justify epoxy because the quantity they typically us is small compared to the production user. To answer your question about why to use epoxy instead of poly is, that it makes a better repair. Regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. But that is really not even much of a factor anymore. To build a 12 foot skiff with flotation and proper materials, it is going to cost you $250.00 on materials and hardware alone (assuming exterior plywood hull), and just for ha ha's, say $25 for a set of plans. If you use poly instead of epoxy, you might save $25 to $30 bucks max on the whole build and more times than not, I have seen first time builders end up using 2-3 times more poly than the plan would call for. The learning curve for mixing poly is treacherous, (bring a good scale and a calculator too) especially to the home builder that may be building outdoors, or in a non conditioned barn, tent, etc. Let me take a minute for anyone who is not clear about mixing the two products. With polyester, you must first calculate your catalyst ratio. So many ounces of resin, to so many drops of catalyst. This mixture is not only very delicate, but it changes depending on ambient temp, humidity, how fast you want things to cure and the required differences in the catalyst mixtures is very minute, and are based on the starting formula plus the users best guess or experience of how to alter that formula to suit the conditions at the time. Any very slight miscalculation in the mix or even how many clouds will pass over during the application can cause total havoc resulting in a slimy hot slop all over your boat that is extremely difficult to remove (think half hardened plastic mixed with cold roofing tar), that is to hard to scrape, and to soft to sand, or a fast kick which catches you with only half of your glass saturated, or just gobs up thicker and thicker as you try to catch up and save something. In both cases the only solution is a lot of elbow grease and lot's of wasted time and sand paper, scrapers, and then a re-application. With Epoxy, the cure rate is also dependant on the temp and humidity of the work area, but not nearly as fast or as radical. Mixing is done with calibrated pumps, something like one pump of resin to one pump of hardener. If you want a faster cure, substitute a "fast" hardener, if slower is your style or a bigger area to do in warmer weather, use a slower hardener, no calculators, no precision scales, no guesswork at all. If your pumps are working properly, and you don't get lazy mixing, even mistakes will harden nicely to be ground or sanded off. One extreme case (admittedly the most extreme I am aware of) was a couple of years ago when I came in very late by e-mail on a build of "Diablo", a 15 foot Bolger type skiff. The plan calls for 2 1/2 gallons of resin. This guy had a terrible summer of heat and cold, never really got the mixtures down in his one build. He spent literally dozens of hours scraping and sanding and just throwing out resin that either kicked to fast, or not at all. He ended up using 11 gallons of poly on the build at a total cost of over $200 for resin alone. Not to mention lost thickeners, thinners, brushes, sand paper, scrapers, time, time, time, time, time... I will stop now, but he has since built another boat, but this time he used epoxy, no problems. Now I don't expect any first timer to build Diablo with 2 1/2 gallons of resin, but certainly 3-3 1/2 should be the max. One final comment. I do not know what the original poster should do, I have no experience there, I don't do restores ;-) I also do realize that poly has it's place in composite shops where big lay-up is done or for molded parts, but somehow this thread seemed to get hijacked to my area so I thought I would chime in here. So this has been my advice, take if for what you paid. Scotty from SmallBoats.com BRBR Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A |
Polyester or Epoxy?
Hey Richard, just out of curiosity for the polyester crowd, how many
aircraft builders, hobby and commercial do you know of that ust polyester? regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. |
Polyester or Epoxy?
Ron Thornton wrote:
Hey Richard, just out of curiosity for the polyester crowd, how many aircraft builders, hobby and commercial do you know of that ust polyester? regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. Not a single one anymore... Even most of the kit manufacturers have changed over to epoxy. OTOH, there is a growing use of vinyl ester resin. It is catalized and works a lot like polyester, but with better chemical resistance and much better physical properties. Richard |
Polyester or Epoxy?
I have mixed both epoxy and polyester for 35 years and have never had a
batch go bad. It ain't brain surgery. All you have to do is follow exactly the manufactures directions. I have to agree with Meindert, if you can't do that, you might want to think about whether you need to be building a boat with two part resins! Only an amateur would extrapolate to broad use the brushing on of catalyst over polyester resin already applied to glass as described by Johns for one boat. There is not a poly resin supplier in the word that would suggest such a thing because there is no way to predict what the final properties would be. As to epoxy, I have mixed batches from 1 gal. down to 6 drops. Yes 6 drops (5:1 West) off of popsicle sticks for RC model aircraft building. For larger batches I use any container of suitable size thats at hand and mark off the ratio with a rule. Gee I'm glad I passed 7th grade math. Allan, the bottom line is that it is historically well established thru industry testing, both lab and field, that epoxy is superior to polyester in most ways except price. No amount of anecdotal evidence or backyard observations as put forth by the polyester crowd will change that. Regards, Ron PS. Meindert, I learned to measure epoxy in the lab at GE a long time ago and was doing it on a balance scale until a couple of years ago I was corrected by Kern of System Three and several other chemist here. They all said that now the published ratios for the formulated resins are for volume only as the weight ratio can be different. I never had any trouble that I could detect but I do by volume ever since to assure max mech properties. I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. |
Polyester or Epoxy?
Ron Thornton ) writes:
Allan, the bottom line is that it is historically well established thru industry testing, both lab and field, that epoxy is superior to polyester in most ways except price. No amount of anecdotal evidence or backyard observations as put forth by the polyester crowd will change that. no argument there. the question is when do you NEED the superior qualities of epoxy? there are other questions about toxicity and so forth but the question that most interests me is when epoxy is NEEDED. I've used it as an adhesive in small quantities and to seal seams in some cases. If I used it instead of polyester and polyurethane on the small boats I've made it would double the price with no benefit I can imagine. everything has its place. I don't consider epoxy to be the only product to use. No amount of anecdotal evidence or backyard observations as put forward by the epoxy crowd will change that. -- ------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage: www.ncf.ca/~ag384/top.htm warning: non-freenet email must have "notspam" in subject or it's returned |
Polyester or Epoxy?
No William, the question is are you qualified to make an informed
decision as to whether poly is good enough. I think not because I like many others here, none of use having any interest in selling epoxy that I know of, have worked with this stuff professionally for years at a technical and engineering level and I doubt that any of us would be willing to just look at all but the most obvious applications and know whether epoxy was needed instead of polyester. You can say poly is good enough all you want but the truth is that you don't really know. All we are saying is that with todays price difference it is more affordable than ever to go with epoxy and add an additional margin to a repair or build. Regards, Ron PS for the hovercraft guy. Build one correctly out of epoxy and see how long its service life is compared to the poly craft. I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. |
Polyester or Epoxy?
I investigated the accident, and cut out a portion of the joint, and it
probably was amine blush, as the tabbing had contamination from sand and silt glued already on it at the bad joint, unlikely to have been in the joint when it was first assembled. I now have builders put a doubler tab on this critical joint, that is 3 times as wide, a small addition of weight for a lot of idiot proofing. Subject: Polyester or Epoxy? From: "David Bosworth" Date: Sat, Jan 17, 2004 10:42 AM Message-id: Hi Barry I would have to say that poor skills and bad work practice caused the failure of the tabbing , not the amine blush of the epoxy. The first BIG mistake the builder made was not following the designers specs for construction to the letter. The second stupid move was not reading the instructions for use of the product he chose to substitute or being the least bit familiar with it. I bet he made alot more mistakes too. scary -- From the rocky shores of the Skykomish river David Bosworth http://www.premier1.net/~daveb/ Barry Palmer wrote in message ... I have had hundreds of my customers using polyester resins on my Sevtec surface skimmer hulls without difficulty, and a few using epoxy, against my advice, with difficulty. In one case, amine blush of the epoxy caused the failure of tabbing that held some hull panels together and the result of using a brake, Yes, a brake on a surface skimmer, at about 35mph, caused the hull bottom to peel off, fortunately with no significant injuries, even though one person of three aboard went through the hole in the bottom and came up treading water behind the craft. Epoxy is very critical in mix ratio, and that is why scales or proportional pumps are used, while polyester catalysis is easily done with a small graduate cylinder, and variations of mix ratio of 20%, which would certainly spell disaster with epoxy, are of no concern with polyester. Some structures do benefit from epoxy, but if the structure strength or stiffness is governed by the glass, not the resin, epoxy may be a waste, except in long term exposure to warm climate salt water. Subject: Polyester or Epoxy? From: (Backyard Renegade) Date: Thu, Jan 15, 2004 3:00 PM Message-id: (Ron Thornton) wrote in message ... Bruce, The "ordinary" people are the ones that can best justify epoxy because the quantity they typically us is small compared to the production user. To answer your question about why to use epoxy instead of poly is, that it makes a better repair. Regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. But that is really not even much of a factor anymore. To build a 12 foot skiff with flotation and proper materials, it is going to cost you $250.00 on materials and hardware alone (assuming exterior plywood hull), and just for ha ha's, say $25 for a set of plans. If you use poly instead of epoxy, you might save $25 to $30 bucks max on the whole build and more times than not, I have seen first time builders end up using 2-3 times more poly than the plan would call for. The learning curve for mixing poly is treacherous, (bring a good scale and a calculator too) especially to the home builder that may be building outdoors, or in a non conditioned barn, tent, etc. Let me take a minute for anyone who is not clear about mixing the two products. With polyester, you must first calculate your catalyst ratio. So many ounces of resin, to so many drops of catalyst. This mixture is not only very delicate, but it changes depending on ambient temp, humidity, how fast you want things to cure and the required differences in the catalyst mixtures is very minute, and are based on the starting formula plus the users best guess or experience of how to alter that formula to suit the conditions at the time. Any very slight miscalculation in the mix or even how many clouds will pass over during the application can cause total havoc resulting in a slimy hot slop all over your boat that is extremely difficult to remove (think half hardened plastic mixed with cold roofing tar), that is to hard to scrape, and to soft to sand, or a fast kick which catches you with only half of your glass saturated, or just gobs up thicker and thicker as you try to catch up and save something. In both cases the only solution is a lot of elbow grease and lot's of wasted time and sand paper, scrapers, and then a re-application. With Epoxy, the cure rate is also dependant on the temp and humidity of the work area, but not nearly as fast or as radical. Mixing is done with calibrated pumps, something like one pump of resin to one pump of hardener. If you want a faster cure, substitute a "fast" hardener, if slower is your style or a bigger area to do in warmer weather, use a slower hardener, no calculators, no precision scales, no guesswork at all. If your pumps are working properly, and you don't get lazy mixing, even mistakes will harden nicely to be ground or sanded off. One extreme case (admittedly the most extreme I am aware of) was a couple of years ago when I came in very late by e-mail on a build of "Diablo", a 15 foot Bolger type skiff. The plan calls for 2 1/2 gallons of resin. This guy had a terrible summer of heat and cold, never really got the mixtures down in his one build. He spent literally dozens of hours scraping and sanding and just throwing out resin that either kicked to fast, or not at all. He ended up using 11 gallons of poly on the build at a total cost of over $200 for resin alone. Not to mention lost thickeners, thinners, brushes, sand paper, scrapers, time, time, time, time, time... I will stop now, but he has since built another boat, but this time he used epoxy, no problems. Now I don't expect any first timer to build Diablo with 2 1/2 gallons of resin, but certainly 3-3 1/2 should be the max. One final comment. I do not know what the original poster should do, I have no experience there, I don't do restores ;-) I also do realize that poly has it's place in composite shops where big lay-up is done or for molded parts, but somehow this thread seemed to get hijacked to my area so I thought I would chime in here. So this has been my advice, take if for what you paid. Scotty from SmallBoats.com Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec BRBR Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A |
Polyester or Epoxy?
It should be recognized that compared to boat builders, the airplane crowd
really throws money at a project. (Yeah, I know it is hard to believe there is an easier way to dispose of excess funds than boating.) The cost of epoxy over polyester is really not a major factor. While a Sevtec surface effect vehicle (or sev) may cost the builder about $4000 minus for a 4 place, 30mph over water 25hp garden tractor engined machine, the airplane builders spend maybe $40,000 and way up, more than half of that sometimes just on the engine. Also, skins on aircraft are very light, you cannot walk on them. Boats must have a much more substantial build, due to this and vastly higher point and overall loading, so the quantity of resin is far more significant. (Sevtec does use vinyl ester resin on a manufactured craft, though, primarily as it is claimed (though maybe not proven) that moisture penetration is less than cheaper resins. Of course, boats use epoxy for the same reason, maybe a single coat near at and below the waterline. Subject: Polyester or Epoxy? From: Richard Lamb Date: Sat, Jan 17, 2004 11:10 AM Message-id: Ron Thornton wrote: Hey Richard, just out of curiosity for the polyester crowd, how many aircraft builders, hobby and commercial do you know of that ust polyester? regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. Not a single one anymore... Even most of the kit manufacturers have changed over to epoxy. OTOH, there is a growing use of vinyl ester resin. It is catalized and works a lot like polyester, but with better chemical resistance and much better physical properties. Richard BRBR Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A |
Polyester or Epoxy?
Longest is still in service after 18 Years, with no problems caused by use of
polyester resin glass skins over 4.5 lb "Clark Foam". These surface skimmers have been built with epoxy, and appear to be little different from the polyester, but possibly the elasticity of the panels is a little greater, (possibly due to inaccurate mixing) bad news when a lot of the structure is not governed by strength, but by stiffness. PS for the hovercraft guy. Build one correctly out of epoxy and see how long its service life is compared to the poly craft. I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. BRBR Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A |
Polyester or Epoxy?
Dunno aboput that, Barry.
My new plane cost me about $6k US. But then I made most all of the parts rather than buying parts. Makes a difference. Richard Barry Palmer wrote: It should be recognized that compared to boat builders, the airplane crowd really throws money at a project. (Yeah, I know it is hard to believe there is an easier way to dispose of excess funds than boating.) The cost of epoxy over polyester is really not a major factor. While a Sevtec surface effect vehicle (or sev) may cost the builder about $4000 minus for a 4 place, 30mph over water 25hp garden tractor engined machine, the airplane builders spend maybe $40,000 and way up, more than half of that sometimes just on the engine. Also, skins on aircraft are very light, you cannot walk on them. Boats must have a much more substantial build, due to this and vastly higher point and overall loading, so the quantity of resin is far more significant. (Sevtec does use vinyl ester resin on a manufactured craft, though, primarily as it is claimed (though maybe not proven) that moisture penetration is less than cheaper resins. Of course, boats use epoxy for the same reason, maybe a single coat near at and below the waterline. Subject: Polyester or Epoxy? From: Richard Lamb Date: Sat, Jan 17, 2004 11:10 AM Message-id: Ron Thornton wrote: Hey Richard, just out of curiosity for the polyester crowd, how many aircraft builders, hobby and commercial do you know of that ust polyester? regards, Ron I don't recieve e-mail at this address because of spam. E-mail me at crtsrATmsnDOTcom. Not a single one anymore... Even most of the kit manufacturers have changed over to epoxy. OTOH, there is a growing use of vinyl ester resin. It is catalized and works a lot like polyester, but with better chemical resistance and much better physical properties. Richard BRBR Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A |
Polyester or Epoxy?
Glenn Ashmore wrote:
Richard Lamb wrote: I don't mean to step on any toes, but since this is a boat building forum... West is a commonly recognized epoxy but imho West is NOT a sutable laminating resin for making fiberglass parts. It's fabulous with wood. But the mechanical properties are low and glass parts tend to be brittle. I've used Dow 330 for years, but can't get it any more. Now I mostly use AeroPoxy. There are several inexpensive laminating resins listed in Aircraft Spruce. There are some expensive resins listed too! Glassing wood? West is best. But for glass or carbon parts, there are much better resins. That is correct. That is also why West has a sister line called Pro-Set which is a laminating epoxy. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com Thanks. Haven't seen that one on the shelves tho. Mostly just West 105. |
Polyester or Epoxy?
This is an epoxy plane? My first "plane" cost me $10.98, 1960 prices, it would
be much higher in 2004 dollars. Look at the Sevtec website and follow the links. No epoxy or polyester was in ght, and I used a free engine, gravity. Subject: Polyester or Epoxy? From: Richard Lamb Date: Sat, Jan 17, 2004 4:27 PM Message-id: Dunno aboput that, Barry. My new plane cost me about $6k US. But then I made most all of the parts rather than buying parts. Makes a difference. Richard BRBR Barry Palmer, for A HREF="http://members.aol.com/sevtec/sev/skmr.html"Sevtec/A |
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