Epoxy or Polyester as I replace large sections of Deck Core

[minaret]

Originally Posted by ramblinrod

I do the math for every customer quote I prepare. The claim that epoxy "bonds
much better" is false (or at least misguided). For properly applied polyester resin FRP repairs are as strong as the polyester resin FRP, being repaired. You just can't do any better than that. Any additional "adhesion strength" is moot, after the repair has been stressed beyond the capability of the material repaired.

I've been repairing polyester FRP with polyester FRP for 40 years, personally and professionally for over 40 years and have never had a bond failure. Not one. Meanwhile, many of my colleagues who have used epoxy, are now allergic to it, and can't be within 100 ft of it, even in a very well ventilated space (including outdoors), while it is curing (up to 2 weeks).

In my opinion, anyone who uses epoxy where it is not required (other materials are perfectly adequate, such as polyester or vinylester resin) is exposing themselves and others to unnecessary health risk.

Oh and using polyester where appropriate saves the customer money, sometimes a lot of money.

I've been telling people on this forum this (replace like with like, bond strength more than sufficient, doesn't create hard spots by making repair laminate stiffer than original, etc etc) for years. It's wasted breath, the epoxy manufacturers have thoroughly brainwashed the entire market. Leave the real work methods to us pro's, you'll never convince the neophytes of the truth. Ever.

[UNCIVILIZED]

Originally Posted by UNCIVILIZED

I'm unclear on some of the cost reasonings behind using Polyester. Perhaps because I've never hunted hard to find it on the cheap. But when you can get epoxy for $40-50/gallon it seems like using it then makes that much more sense. Given it's enhanced physical properties. Including bonding much better to marginal surfaces. This, & the fact that if you use it for this kind of job, you've got a much better chance of everything coming out well the first time. And I'd HATE to have to do such a job twice simply because I cheaped out, & went with Poly the 1st time.

Besides, I've pulled WAY too much glass off of cores, or wood, that was put on with polyester. And by pulled off, I mean using nothing more than my fingers, or perhaps a pair of pliers. So I ain't impressed with it's tenacity for sticking to wood. Even if much of what I pulled off was put in in a manner differing from proper industry standards. Since I know that epoxy put onto the same surfaces, in the exact same way, sticks a f**k of a lot better. BTDT, so using Epoxy's a no brainer for me.

Even if using epoxy instead of poly adds $5/sqft to the job, that ain't much compared to the overall job cost. Heck, even if it adds $10/sqft those still aren't loco numbers. Do the math!

Originally Posted by ramblinrod

I do the math for every customer quote I prepare. The claim that epoxy "bonds
much better" is false (or at least misguided). For properly applied polyester resin FRP repairs are as strong as the polyester resin FRP, being repaired. You just can't do any better than that. Any additional "adhesion strength" is moot, after the repair has been stressed beyond the capability of the material repaired.

I've been repairing polyester FRP with polyester FRP for 40 years, personally and professionally for over 40 years and have never had a bond failure. Not one. Meanwhile, many of my colleagues who have used epoxy, are now allergic to it, and can't be within 100 ft of it, even in a very well ventilated space (including outdoors), while it is curing (up to 2 weeks).

In my opinion, anyone who uses epoxy where it is not required (other materials are perfectly adequate, such as polyester or vinylester resin) is exposing themselves and others to unnecessary health risk.

Oh and using polyester where appropriate saves the customer money, sometimes a lot of money.

ramblinrod, you'd do well to Read My Post, & to kindly refrain from attacking it out of context thanks. I said that epoxy bonds much better to marginal surfaces (than does polyester). Period. Which, when repairing composites, is often the case (bonding to marginal surfaces I mean). Especially when said repairs are being done by those new to working with these materials & products. Such is simply fact. Since neopytes don't have the knowledge base & experience that pro's do. Got it?

I also stated that anyone undertaking repairs should run the numbers themselves on the cost differences between using various resin types. Which again, is only common sense. And due to said intelligence type, one would be silly to automatically reach for any particular product without first thinking through the entire project.

I get that you're saying that polyester resin has worked well for you, & that's great. But there are ways of expressing same without badgering anyone else who doesn't automatically fall in line with your modality of thinking without question.

Not to mention that the way that you state that you've had zero bond failures with the stuff can easily be interpreted as saying that my comments about being able to peel off polyester bonds by hand are flat out lies. Which, one needn't work on boats long before running into polyester on polyester bonds that in fact are easy to peel off by hand. Ditto on polyester bonds to wood substrata. And I'd be shocked if you hadn't run into the same with some polyester bonds in your travels. Non? Where as this is much, much less prevalent with epoxy.

Bedside manner counts for a lot. And if you go overboard in stating why your method is superior, even if it in fact is, you'll have soured a lot of people on it due to your approach. So how does that help any of the involved parties? Seriously? Not just in this thread, but whenever this topic comes up when you're involved. Geez


PS: It's common knowledge that poly to poly bonds ain't ideal, strength wise, especially as they age. Look at how common it is for bulkhead tabbing to come adrift on middle aged boats. After several years, some have less adhesion strength than duct tape. SIC

[ramblinrod]

Originally Posted by UNCIVILIZED

I'm unclear on some of the cost reasonings behind using Polyester. Perhaps because I've never hunted hard to find it on the cheap. But when you can get epoxy for $40-50/gallon it seems like using it then makes that much more sense. Given it's enhanced physical properties. Including bonding much better to marginal surfaces. This, & the fact that if you use it for this kind of job, you've got a much better chance of everything coming out well the first time. And I'd HATE to have to do such a job twice simply because I cheaped out, & went with Poly the 1st time.

Besides, I've pulled WAY too much glass off of cores, or wood, that was put on with polyester. And by pulled off, I mean using nothing more than my fingers, or perhaps a pair of pliers. So I ain't impressed with it's tenacity for sticking to wood. Even if much of what I pulled off was put in in a manner differing from proper industry standards. Since I know that epoxy put onto the same surfaces, in the exact same way, sticks a f**k of a lot better. BTDT, so using Epoxy's a no brainer for me.

Even if using epoxy instead of poly adds $5/sqft to the job, that ain't much compared to the overall job cost. Heck, even if it adds $10/sqft those still aren't loco numbers. Do the math!

I do the math for every customer quote I prepare. The claim that epoxy "bonds
much better" is false (or at least misguided). For properly applied polyester resin FRP repairs are as strong as the polyester resin FRP, being repaired. You just can't do any better than that. Any additional "adhesion strength" is moot, after the repair has been stressed beyond the capability of the material repaired.

I've been repairing polyester FRP with polyester FRP for 40 years, personally and professionally for over 40 years and have never had a bond failure. Not one. Meanwhile, many of my colleagues who have used epoxy, are now allergic to it, and can't be within 100 ft of it, even in a very well ventilated space (including outdoors), while it is curing (up to 2 weeks).

In my opinion, anyone who uses epoxy where it is not required (other materials are perfectly adequate, such as polyester or vinylester resin) is exposing themselves and others to unnecessary health risk.

Oh and using polyester where appropriate saves the customer money, sometimes a lot of money.

[Terra Nova]

Polyester resin has a very long track record for extremely poor bonds with wood substrates. Hence the reason I have been using WEST epoxy for 40+ years.

[smj]

Originally Posted by minaret

I've been telling people on this forum this (replace like with like, bond strength more than sufficient, doesn't create hard spots by making repair laminate stiffer than original, etc etc) for years. It's wasted breath, the epoxy manufacturers have thoroughly brainwashed the entire market. Leave the real work methods to us pro's, you'll never convince the neophytes of the truth. Ever.

So if someone doesn't take what you say as fact they are automatically a neophyte?
The boat builder I worked for designed and built commercial day charter boats as well as doing repairs and small jobs. I'm sure he has as much or more experience than you and would refuse to use polyester in any type of structural secondary bond. Is he also a neophyte?

[glhotka]

Originally Posted by neilpride

May i ask you with what kind of core or Wood you are recoring the deck?

The section I did a repair on (2 x 5 feet) had small 1/2 mahogany hardwood pieces in it. They were laid end to end and each one was 3" by 9-12" depending on the board. I put mahogany back in 1/2 thick and the ones I put in were about 5" wide.

My latest post where I discussed replacing a larger section, I was going to do with 1 layers of 1/2" marine grade plywood with thickened epoxy adhering the plywood down to the lower skin of the core, then thickened epoxy between the 2 layers of 1/2 ply and then was considering poly resin and glass on top of the new plywood core since it would not be having to stick to previous layers of another resin type.

That was the thought at least.

[Rhapsody-NS27]

Originally Posted by minaret

I've been telling people on this forum this (replace like with like, bond strength more than sufficient, doesn't create hard spots by making repair laminate stiffer than original, etc etc) for years. It's wasted breath, the epoxy manufacturers have thoroughly brainwashed the entire market. Leave the real work methods to us pro's, you'll never convince the neophytes of the truth. Ever.

I was thinking this myself... What kind of resin was the boat built with? Poly? Which one, Isophtalic (iso) or Orthophthalic (ortho)? What's wrong with just sticking with the same kind?

To me it would make more sense just to stick with the same resin as was used when built. Not sure about polyester, but the vinylester resin I'm currently using in a project gets a little softer when wiped down with acetone, which I think is supposed to help with bonding of additional layers. I'm hardly a pro so if I'm wrong, clarification is appreciated.

I'd think either poly or vinyl esters would be just fine.

[lateral]

Where wood is involved I always use epoxy. Fundamental, if you adhere to DOS
principle. But this probably doesn't apply to all timber varieties, just not willing to take the risk.
But on a poly substrate I am happy to use Poly, if not prefer.

When in doubt I switch to epoxy or do a quick peel test.

[Colin A]

Originally Posted by UNCIVILIZED

I'm unclear on some of the cost reasonings behind using Polyester. Perhaps because I've never hunted hard to find it on the cheap. But when you can get epoxy for $40-50/gallon it seems like using it then makes that much more sense. Given it's enhanced physical properties. Including bonding much better to marginal surfaces. This, & the fact that if you use it for this kind of job, you've got a much better chance of everything coming out well the first time. And I'd HATE to have to do such a job twice simply because I cheaped out, & went with Poly the 1st time.

Besides, I've pulled WAY too much glass off of cores, or wood, that was put on with polyester. And by pulled off, I mean using nothing more than my fingers, or perhaps a pair of pliers. So I ain't impressed with it's tenacity for sticking to wood. Even if much of what I pulled off was put in in a manner differing from proper industry standards. Since I know that epoxy put onto the same surfaces, in the exact same way, sticks a f**k of a lot better. BTDT, so using Epoxy's a no brainer for me.

Even if using epoxy instead of poly adds $5/sqft to the job, that ain't much compared to the overall job cost. Heck, even if it adds $10/sqft those still aren't loco numbers. Do the math!

I'm curious what Epoxies are $50/ a gallon. I mean I don't look around much I usually use MAS or system 3 which run's $85-$130 a gallon with hardener. Where as my local supplier sells polyester for $26 a gallon with hardener.

[ramblinrod]

Originally Posted by UNCIVILIZED

ramblinrod, you'd do well to Read My Post, & to kindly refrain from attacking it out of context thanks. I said that epoxy bonds much better to marginal surfaces (than does polyester). Period. Which, when repairing composites, is often the case (bonding to marginal surfaces I mean). Especially when said repairs are being done by those new to working with these materials & products. Such is simply fact. Since neopytes don't have the knowledge base & experience that pro's do. Got it?

I also stated that anyone undertaking repairs should run the numbers themselves on the cost differences between using various resin types. Which again, is only common sense. And due to said intelligence type, one would be silly to automatically reach for any particular product without first thinking through the entire project.

I get that you're saying that polyester resin has worked well for you, & that's great. But there are ways of expressing same without badgering anyone else who doesn't automatically fall in line with your modality of thinking without question.

Not to mention that the way that you state that you've had zero bond failures with the stuff can easily be interpreted as saying that my comments about being able to peel off polyester bonds by hand are flat out lies. Which, one needn't work on boats long before running into polyester on polyester bonds that in fact are easy to peel off by hand. Ditto on polyester bonds to wood substrata. And I'd be shocked if you hadn't run into the same with some polyester bonds in your travels. Non? Where as this is much, much less prevalent with epoxy.

Bedside manner counts for a lot. And if you go overboard in stating why your method is superior, even if it in fact is, you'll have soured a lot of people on it due to your approach. So how does that help any of the involved parties? Seriously? Not just in this thread, but whenever this topic comes up when you're involved. Geez


PS: It's common knowledge that poly to poly bonds ain't ideal, strength wise, especially as they age. Look at how common it is for bulkhead tabbing to come adrift on middle aged boats. After several years, some have less adhesion strength than duct tape. SIC

I posted a contrary position and experience, in a civilized manner.

Sorry if it troubles you, but.....

Millions of boats (literally) have been manufactured out of polyester resin FRP over wood core, many over 40 years ago, that are still going strong today.

In my personal and professional experience I have witnessed polyester FRP failures due poor preparation, mixing, and application. I have also witnessed same with epoxy.

Improper prep or application may cause any material to fail. Since the processes for properly preparing and applying polyester resin vs epoxy resin are virtually identical, I cannot logically conclude either would be easier to use for the inexperienced.

[UNCIVILIZED]

You can have 2 composites fabricators right next to one another doing hand layups using the same materials, under the same conditons, & yet the end products may have vastly differing strength numbers & physical properties. Sometimes by a factor of 2x or more. This due mostly to technique.

The more experienced guy may take better care of his reinforcements from the time they leave the roll, until they're used in the part or repair. Keeping them more contaminant free. Flexing them less. Never touching them with bare, dirty/oily hands. Wetting them out more evenly. Rolling out a larger percentage of air in the layup. Better mechanical keying into the surface to which things are being applied, ditto with regards to cleanlyness, etc., etc. All combining to make a much better finished product.

The same's true in welding, & a lot of other disciplnes. Thus my comments on this.

So if someone's new to working with composites, it's very easy to make a bunch of small mistakes without even realizing that you're doing as much. Thus even though the materials (resin) used is the same as the base laminate, the repair may be lower in strength than that which it's attached/bonded to. And the bond strength itself may be weaker as well if the resin is of the same type as the original used to build X that's being repaired. In this case, polyester resin.

But if he uses epoxy, the epoxy may overcome some of his technique flaws by virtue of it's better physical & mechanical properties. Obviously this isn't guaranteed, but it stacks the odds a bit better in one's favor.

[UNCIVILIZED]

Originally Posted by Colin A

I'm curious what Epoxies are $50/ a gallon. I mean I don't look around much I usually use MAS or system 3 which run's $85-$130 a gallon with hardener. Where as my local supplier sells polyester for $26 a gallon with hardener.

I've not tried anything new in terms of resin in a while, as I've still got some around from my last bulk purchase. But here are a few links I've run across in just the last few months. The prices range from about $40-$80/gal
OffshoreCatamarans.com Featured Products
MARINE GRADE EPOXY RESIN | East Coast Resin
http://lbifiberglass.com/EPOXRESINS/epoxy.html
Epoxy :Â*Epoxy Resins and Hardeners
And it helps to get to know builders & boat repairers. Both to get a feel for the properties of resin X, or Y prior to buying some. And in that guys who use the stuff in bulk usually get better prices on it.

Plus, if contemplating a big, or critical project, & the resin's an unknown, buy a small quantity, & test it out a bit first. Along with doing as much research on it as possible.

You also want to consider what application it'll be used for, & how critical the resin's performance will be for the job in question. For instance if you're gluing up cored composite panels to build an interior out of, the resin needn't be on par with that used in hull construction of a high tech racer.

[toddedger]

So terra nova, you've been using epoxy for 40 years and you have never seen an epoxy repair that has continued to shrink once its been in the sun? I say 40 years, Bull to you!

For those who want to know it's 120° Fahrenheit. That temp came from the Gougeon Brothers about twenty years ago when I was talking to them on the phone.

Epoxy and polyester both continue to shrink over time. Look at all the old glass boats that are starting to show the glass print through. Because of the long term shrinkage most manufacturers use mat now as the first layer in a mold. Its when you start using fillers with epoxy that you run into bad shrinking problems.

Cutting a bunch of holes to dry out core and filling them up with with epoxy use to be fairly common, and it's fairly common to see where someone did these kinds of repairs a few years down the road. Have ask Gougeon Brothers about these unsightly polka-dots they explained to me about post curing. Now I always take the time to post cure repairs before I pull off the peelply.

[Terra Nova]

Your pure bull is the part regarding Gougeon recommending 120* post cure, particularly on deck repairs.

[neilpride]

Originally Posted by toddedger

So terra nova, you've been using epoxy for 40 years and you have never seen an epoxy repair that has continued to shrink once its been in the sun? I say 40 years, Bull to you!

For those who want to know it's 120° Fahrenheit. That temp came from the Gougeon Brothers about twenty years ago when I was talking to them on the phone.

Epoxy and polyester both continue to shrink over time. Look at all the old glass boats that are starting to show the glass print through. Because of the long term shrinkage most manufacturers use mat now as the first layer in a mold. Its when you start using fillers with epoxy that you run into bad shrinking problems.

Cutting a bunch of holes to dry out core and filling them up with with epoxy use to be fairly common, and it's fairly common to see where someone did these kinds of repairs a few years down the road. Have ask Gougeon Brothers about these unsightly polka-dots they explained to me about post curing. Now I always take the time to post cure repairs before I pull off the peelply.

Mate with all the respect, WTh you talking about?