What is difference between Epoxy & Polyester Resins

Fanie
>>>>Richard, you seem to forget that time is marching on, and with it comes new technologies that makes things possible that were not possible before.<<<<

do you believe I am a complete idiot?

We built a complete new yard to produce the larger boats series in VE, 2 years ago. Another newbuilt for the wood epoxy production this year (just the latter was 33 mio€). Do you assume we use grandfathers rules of thumb?

Richard

[ondarvr]

Originally Posted by apex1

Sorry to contradict you here,
that is just NOT TRUE! Not even the manufacturers of poly resins claim that it sticks well.

I really cannot understand why this idiotic statement pops up here ever and ever again.

Poly sticks good to nothing, absolutely nothing, not one single boatbuilding material, not even to cured poly, not to untreated glassfibre, just to nothing!

It does not stick!

And it is water permeable, no matter which one u use. Gelcoat is even worse than straight poly, it just looks nice (for a while).

Does anyone here assume we do our wood epoxy boats because we love epoxy? Anyone familiar with barrier coats? That´s epoxy. Why?

Please stop telling people which come here for serious advice, they could use poly for repairs. They could use plaster as well. (in fact that is done on wooden boats)

Regards
Richard

I'm not sure which Polyester manufactures say it doesn't stick to anything.

I work for a very large world wide manufacturer of polyester and VE and I do tech service, we do not recommend repairs should be done with epoxy, it is possible that some should be, but most can be done very well with standard products. I've also repaired more things than most here can imagine are being made from these resins and the failure rate is so low its not much of a concern. So if a polyester to polyester bond is so poor that it can't possibly last in use, I would have seen this to be true first hand.

We test bonds frequently in the lab and I've done real world destructive testing in the field and the statements like “it won't bond to anything" and "it should never be used" just aren't supported by the facts.

It makes no difference if epoxy bonds 100 (just a number) times better than polyester if the bond strength of the polyester is never exceeded in the part or repair, which is normal.

[gonzo]

This resin type discussion is more heated than a religious war.

[Fanie]

This resin type discussion is more heated than a religious war.

No it isn't, not really, no I don't think so

I know the thread started out with what to use for a repair, but the argument got started by some that polyester resin is a substandard product.

Polyester is a brilliant product. It produces boats all over the world and some even stay afloat for more than a day and a few years after that and a few decades after that. Some weigh the same as epoxy boats and will last just as long, will never break, looks just as good, and will fetch the same market price if sold.

do you believe I am a complete idiot?

I don't think you are an idiot Richard. Ok well, not a COMPLETE one
Nobody can be that good anyway

If you build using wood and epoxy, then that is the right combination for your building method. If it was me, I would not have used polyester and wood either.

I did not know your Grandfather.



Thank you Ondarvr. 4 5 c, what took you so long

[ondarvr]

Originally Posted by gonzo

This resin type discussion is more heated than a religious war.

I enjoy it, I don't love one product more than the other because they both have their place in the industry. The information passed along needs to be accurate though.

ondarvr

that:

I'm not sure which Polyester manufactures say it doesn't stick to anything.

was not my statement!
Reading thoroughly and quoting correct makes a discussion fair. You did bend the meaning in a unfair way.
Not a nice way to discuss.

And I do´nt know why I have to say this another 20 times, but here it goes again: WE USE BOTH RESINS! VINYLESTER AND EPOXY, each where it makes sense. And Epoxy is by far the superior resin in ALL applications. period

Ah, not to forget: Polyester sticks good to nothing

Regards
Richard

[ondarvr]

Sorry if I misquoted you, I just got back in from a 4 hour drive, I was at an account of mine that makes Yachts up to around 200' from VE and I was tired.
We were spraying a new style of gel coat and looking at a new plug for a tool, I think it was in the 140' range.

I agree that epoxy has better properties in most ways, but what needs to be understood is that better means nothing if the properties aren't required for the application.

[elhix]

I'm finishing building a 32 foot Shuttleworth cat. The hulls, bridgedeck and bulkheads used polyester. The chainplates, daggerboard and case, rudders and forward beam used epoxy. Whilst epoxy has superior properties, as many have pointed out, in many areas of a boat these aren't taken advantage of so the considerable extra expenditure is unnecessary. In my case the structures most subjected to dynamic loads have utilised epoxy.

My cat has been painted with multiple coats of epoxy-based hi build so the water penetration issue is covered, not that it is a significant concern for me anyway. A surveyor I spoke to told me it was far rarer to find genuinely serious cases of osmosis than the widespread fretting about it warrants.

Last of all John Shuttleworth himself - one of the most highly regarded multihull designers in the world, particularly known for his structural savvy - recommended polyester for my build. I'm very grateful to him for this as otherwise I'd have thrown an extra £6000 ($10,000) into the boatbuilding chasm and begun suffering from epoxy allergy much sooner.

Fully concur.
Horses for races..........what else.

But your surveyor should do some survey from time to time! And he should know that nearly NOBODY talks about osmosis!!!! (well, yes yachties do, pro´s do´nt)..
Does´nt the local MC Don... provide a adequate job for him?

[elhix]

eh???

[Scrumble]

2Sheets2Wind,

You asked "What is difference between Epoxy & Polyester Resins"

Strength

[AndrewK]

From my local observation very few boat builders ( professional & amateur ) post cure their boats.
There are many epoxy resin formulations and many curing agents being used, and unless you post cure epoxy resin systems you can not assume that ALL epoxy mechanical properties are superior to PE & VE resin.
For ambient temperature cure the only two properties that you can safely say that epoxy resin is superior in are water proofing and low shrinkage. This is based on information from the data sheets for the locally available marine epoxy systems.

My recommendation to anyone building a boat from scratch is to ask for full resin properties for the cure conditions you are going to achieve and make your selection based on facts. This includes getting the properties for the individual hardeners in a epoxy system.

If only doing a repair to a polyester boat then, if the intention is to gelcoat the repair I would use either iso-PE or VE resin. If the repair is going to be painted then use epoxy if you wish. Either way they all are fit for purpose.

Like Fanie I too would like to see comparative laminate test date showing the difference that the resin properties make to a laminate.

Cheers
Andrew

[Jimbo1490]

Although quite smelly, polyester resin is potentially less toxic than the typical epoxy resin, at least with the exposures that an occasional user will ever see. The usual epoxy formulations, like West, system 3 and others, use very toxic amine curing agents like DETA and TETA which are dangerously toxic, even though they smell rather sweet. These agents are easily absorbed through the skin as well as by inhalation. You can take sensible precautions and practice good industrial hygiene for these and avoid these issues with epoxy completely.

But it seems that people are more likely to practice these precautions with polyester resin than they are for epoxy resin, because polyester has certain 'warning' properties (it smells bad and it burns your skin upon prolonged contact) while epoxy does not (it smells OK and does not irritate skin much until that fateful day you discover you have become sensitized ) , even while the epoxy curing agent is doing real damage to your liver and kidneys and the polyester is just burning your throat and eyes and making your skin red, and not much else. I'm telling you this not to scare you away from using epoxy resin, but motivate you to use it right.

Jimbo

[Jimbo1490]

Originally Posted by AndrewK

From my local observation very few boat builders ( professional & amateur ) post cure their boats.
There are many epoxy resin formulations and many curing agents being used, and unless you post cure epoxy resin systems you can not assume that ALL epoxy mechanical properties are superior to PE & VE resin.

Cheers
Andrew

Elongation and fracture toughness are always better, even before post-cure. And both of these improve dramatically after post-cure. These are important parameters for achieving good toughness and damage tolerance. If the hull NEVER sees hot summer type weather, then it will never be 'post-cured' unless the builder does it. But if it does see such weather(especially while dry), then it will be post cured during the weeks of its first exposure to that weather, when hull temps will probably be over 38C for hours on end.

Jimbo

"What is difference between Epoxy & Polyester Resins" - To me, owning a poly boat and not wanting to have future adhering problems, I do mods and repairs with poly unless the strength of the repair is critical. All around it boils down to incompatabilty issues - want to fill a small gap or make a nice radius? Break out the Cab-O-Sil (fumed silica) and whip it thixotropic. Everything else is gelcoated - why change now? I've always wondered just how strong epoxy is, once you mix enough wood flour to make it thixotropic - can you fill a screw hole with it, then paint or gelcoat and have it last?
I have an acquaintance (Ren Tolman) who swam in epoxy for years and is paying the price in more ways than one. I swear, looking at his hands, I itch. I get near epoxy and I itch (psychosomatically) but I also know that the days of mixing up more than you will need and throwing away sheet after sheet of cardboard palettes with a big glob of half-hard thixo are gone. It is time to work smarter, neater.
One thing I wonder about, if I were to ever build another boat, is making it lighter by using carbon, maybe not that much more expensive because of less need for carbon and resin but I also wonder, with this stiffer material, "does that deadhead penitrate the hull?" Do I need the dumb brute heavy layup afforded by poly or will some combination of wunderproduct (Kevlar?) make up for those missing layers of glass?
I'm not much of a fan of infusion (for my purposes), so that leaves, what appears to me, carbon prepreg. I just can't get visions of Goetz neatly laying the pieces, everything engineered and oriented just so, in an upside down sailboat he was building. No dust, no walking on the work. Everything exactly like you want, then turn up the heat and walk away. To me, this is the future (even tho that proboat was maybe fifteen years old) - at least my future and it requires epoxy.
Richard, how do you repair Vinylester? I thought nothing would stick to it once cured?
Par, I have been watching the Spectra developement since there was Spectra. I'm with you on that stuff. Just too slippery still?