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Old 29-10-2013, 12:09   #1
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vinylester polyester resin for repairs

Kurt Hughes website says That using This type resin for repairs in the typical boatyard outdoor environment is a no no. he says for it to work and provide its qualities it needs to be applied in a closely controlled temperature and humidity environment....He usually advocate epoxy
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Old 29-10-2013, 21:26   #2
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Re: vinylester polyester resin for repairs

Kurt is right one of the grea things about epoxy is that it sticks to everything. Poly and vinyl have major issues binding to anything. It can be done, and for many things a pure mechanical bond may be fine, but frankly unless you are building a boat I don't understand even owning anything but epoxy. The price difference just isn't that significant.
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Old 29-10-2013, 21:43   #3
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Re: vinylester polyester resin for repairs

I'm so tired of this argument. I'll just note that a guy in the yard started a refit of his (much much smaller) boat around the same time as me last year. I did everything in poly on a job at least twenty or thirty times as big as his and am almost totally done with a full refit down to the last detail. His boat is still stripped down completely and he's still glassing and fairing. He has switched to poly where possible now (ie wherever he didn't already commit to epoxy by using it on a poly boat). The cost of materials is only a tiny fraction of the cost of a big glass job, it's all in the hours. And working in poly is much, much faster than epoxy. It's also perfectly sufficient and will last your lifetime and more when done right.
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Old 29-10-2013, 21:45   #4
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Re: vinylester polyester resin for repairs

Quote:
Originally Posted by georgetheleo View Post
Kurt Hughes website says That using This type resin for repairs in the typical boatyard outdoor environment is a no no. he says for it to work and provide its qualities it needs to be applied in a closely controlled temperature and humidity environment....He usually advocate epoxy



VE is a bit more finicky than poly. But I've used it outdoors here in Seattle where the environment couldn't be any more humid with no problems plenty of times. You just need a big heater, and a little more patience than when working in poly.
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Old 30-10-2013, 00:21   #5
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Re: vinylester polyester resin for repairs

Quote:
Originally Posted by minaret View Post
I'm so tired of this argument. I'll just note that a guy in the yard started a refit of his (much much smaller) boat around the same time as me last year. I did everything in poly on a job at least twenty or thirty times as big as his and am almost totally done with a full refit down to the last detail. His boat is still stripped down completely and he's still glassing and fairing. He has switched to poly where possible now (ie wherever he didn't already commit to epoxy by using it on a poly boat). The cost of materials is only a tiny fraction of the cost of a big glass job, it's all in the hours. And working in poly is much, much faster than epoxy. It's also perfectly sufficient and will last your lifetime and more when done right.
I can't even begin to imagine what this has to do with the relative properties of epoxy vs polyester.

1) first what Poly manufacturer has an unlimited shelf life? All the ones I have dealt with have a 1 yer shelf life

2) secondly there is no issue I have every heard with bandying epoxy to polyester. There is an issue with trying to bond some polyesters to epoxy however. In large part because Poly has very little bond strength.

3) I have never had a problem working quite quickly with epoxy. Pick the resin you want, match the hardner to the temp and cure time you want, get to work.

For a technical (but not terribly deep) background see http://www.amtcomposites.co.za/sites...0Polyester.pdf
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Old 30-10-2013, 13:23   #6
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Re: vinylester polyester resin for repairs

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Originally Posted by Stumble View Post
I can't even begin to imagine what this has to do with the relative properties of epoxy vs polyester.....

2) secondly there is no issue I have every heard with bandying epoxy to polyester. There is an issue with trying to bond some polyesters to epoxy however. In large part because Poly has very little bond strength.
Most repairs fail due to poor preparation, not because there is a poor bond. As Minaret said above poly is perfectly sufficient for this type of repair. But don't take his word for it, he only does it for a living. Oh yeah, poly is good enough for his boat.

Also, be careful, poly is most likely keeping the water out of your boat.
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Old 30-10-2013, 13:34   #7
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Re: vinylester polyester resin for repairs

Opie,

I used to do this for a living too. I also work in the Marine Industry for a living.

Can poly work? Sure it can, it just takes meticulous preparation, good application, and knowing what you are doing. So what? Epoxy is easier to work with, more forgiving, has better matter properties anyway, BUT is is marginally more expensive.

And every boat I know of wether it be poly or vinyl uses an epoxy barrier coat (weirdly even most of the epoxy boats use an epoxy barrier coat for some strange reason).
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Old 30-10-2013, 23:13   #8
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Re: vinylester polyester resin for repairs

Quote:
Originally Posted by minaret View Post
I'm so tired of this argument. I'll just note that a guy in the yard started a refit of his (much much smaller) boat around the same time as me last year. I did everything in poly on a job at least twenty or thirty times as big as his and am almost totally done with a full refit down to the last detail. His boat is still stripped down completely and he's still glassing and fairing. He has switched to poly where possible now (ie wherever he didn't already commit to epoxy by using it on a poly boat). The cost of materials is only a tiny fraction of the cost of a big glass job, it's all in the hours. And working in poly is much, much faster than epoxy. It's also perfectly sufficient and will last your lifetime and more when done right.
+1

I don't know where 'meticulous preparation' comes into play. It really isn't that hard to prep an area for polyester. If you're doing a repair, you need to remove the damage first. That's the prep work, right there, and you have to do that regardless of what you're working with. The grinder will expose glass that you can work on. I've also never seen poly "fail".
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Old 30-10-2013, 23:17   #9
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Re: vinylester polyester resin for repairs

I'm no sort of expert, but my experience is that I've never had any problems with epoxy resin, but I have had problems with vinylester - particularly in combination with filler powder (microballoons, etc) for fairing & coving.
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Old 31-10-2013, 08:20   #10
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Re: vinylester polyester resin for repairs

Quote:
Originally Posted by Stumble View Post
I can't even begin to imagine what this has to do with the relative properties of epoxy vs polyester.

1) first what Poly manufacturer has an unlimited shelf life? All the ones I have dealt with have a 1 yer shelf life

I guess if you want a product to put on the shelf and look at instead of using it to repair your boat, this might matter. Which epoxy are you using that has "unlimited shelf life"? No such thing.



2) secondly there is no issue I have every heard with bandying epoxy to polyester. There is an issue with trying to bond some polyesters to epoxy however. In large part because Poly has very little bond strength.

Even the most rank amateur knows you can't put poly on epoxy, and the reason is because the amines in the epoxy prevent poly from curing properly. You are no pro.




3) I have never had a problem working quite quickly with epoxy. Pick the resin you want, match the hardner to the temp and cure time you want, get to work.


Even Fast hardener doesn't cure anywhere near as fast as poly. And if you use it for a large layup you will blow it every time, because you can only mix very small batches. Therefore you must use a slower hardener for a layup of any size, and you are still locked in to smaller batches. I regularly mix poly resin in two quart batches and get and hour and a half of working time. My layup is kicked and ready to grind an hour later. Try doing that with epoxy! If you mix fast epoxy in a two quart batch, it'll be smoking before you're done stirring.


For a technical (but not terribly deep) background see http://www.amtcomposites.co.za/sites...0Polyester.pdf


Nice link to an epoxy manufacturers page on why their product is better. Exactly the sort of propaganda which annoys me.
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Old 31-10-2013, 08:27   #11
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Re: vinylester polyester resin for repairs

All of the issues I mention here are well known to the epoxy companies. Look carefully at WEST literature, and you'll see that they don't recommend using their resin for laminating. It's why they have a dedicated laminating resin. It's called Proset, and I've used several thousand gallons of it. It has much more appropriate viscosity for laminating, as well as features which attempt to address some of the issues I've mentioned here. And it is still vastly slower than working in poly. Great product though, for those who can afford to go that route.
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Old 31-10-2013, 10:29   #12
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Re: vinylester polyester resin for repairs

Minaret do you use poly below the water line also?
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Old 31-10-2013, 12:33   #13
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I've done a reasonable amount of small glass products, centre consoles. Dock boxes etc, I've always found polyester easier to work with the epoxy , more tolerant of mis -mixing , less temperature sensitive and less sensitive to non expert application.

I prefer it over epoxy

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Old 31-10-2013, 14:10   #14
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Re: vinylester polyester resin for repairs

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Minaret do you use poly below the water line also?


Yes, often, as long as it will be barrier coated. I always barrier coat, for VE or epoxy too. Interesting that the best barrier coat is a modified epoxy loaded with solvents, totally contrary to some of the other things recently posted by the same person. I've seen plenty of failures in epoxy fairing compound above and below the waterline. All the same rules apply for both. And once again it is not even mentioned that there are many different kinds of "poly" resin. Modern VE or poly iso bonds extremely well. All these myths are about production grade poly ortho.
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