Epoxy VS. Polyester

I've used West System epoxy extensively in, on and around Commander hull #215. In the five years I've had my boat I've gone through at least 5 gallons of resin and used all of the hardeners and fillers in that line. I've had nothing but good luck with West, and I think their literature is excellent and gave me the information required to get the most out of their high quality product.

My remaining intrest in polyester is a result of the huge disparity in price and working properties of air inhibited resins. With West at about 100.00 a gallon for resin and hardner and laminating resin at $35.00 a gallon I'd like to see if I could get the same results with the less expensive product , after all, my Commander started it's nearly 40 year life as a polyester boat. Price aside, it would seem that for working overhead, repairing core and building laminates, that a resin that remained tacky on its surface would enable one to build layers up more easily and with a slower more complete mechanical bond the result. All this without having to wash the amine blush off and a frosty sanding. Less work!

Does anyone know of a good technical guide for working with polyester resin? I have Paul Petricks book "Fiberglass Repairs", its pretty good but I'd like something along the lines of the Gougeon Bros. technical manuals. Can you use the same fillers for polyester as you can for epoxy? Anyone with info or experience, please weigh in on the relative merits of these two products, shared knowledge and saved money may be the result.
Cheers B.
Commander #215

i have heard that poly is good for above the waterline and epoxy below.

probably because epoxy is more resistant to water, while poly forms a more complete bond (chemical and mechanical). the layers of epoxy only have an adherent mechanical bond, whereas a new poly layer will actually chemically bond with the old layer so that the two are one piece.

there is an interesting aritcle on good old boat about this. i will try to find it or a web link. it also had to do with safety. the poly has fumes that are harmful, while the mixture isn't harmful to your skin, but the exopy is exactly opposite.

i will follow up on the web address here soon.
-km
hull#3

I'm sure poly would work fine, but epoxy does have superior qualities.

Here are a few articles I've collected:

http://www.redrockstore.com/resin.htm

http://www.boats.com/content/default...contentid=2907

West epoxy is overpriced. Raka or Mass epoxy is about $ 80 for 1.5 gallons.

This guy sells epoxy for much less.

http://www.epoxyproducts.com/marine.html

I don't have any experience with his products.

Mike will probably have a link to a good wholesale company.

I have never heard that polyester chemically bonds to itself. Unless you are doing wet laminations with unwaxed poly.

Polyester is NOT a glue.

Epoxy is a glue. And if somebody wants to call dry layers of epoxy 'mechanical' so be it. My research says epoxy sticks a lot better to cured polyester than polyester does.

The epoxy I used does not have a chemical smell. Has no solvents in it. Doesn't shrink, doesn't blush, cures at 40 degrees on up.

Polyester styrene will kill you. You need 70 degrees for a successful cure. Acetone, your solvent of choice, and MEK will melt your brain cells. I would rather have a mechanical cure (what the hell is the matter with that?) than a chemical. What's that anyway?

This is not to say that polyesters don't have their place in well ventilated work spaces for projects like seahoods, hatch covers and tanks.

Please show us(me) where polyester is the prefered refit material.
Polyester based vinylester is a better adhesive, used in molded boats as the first layer in the mold (I hear) But again, if it's a barrier coat after that fact you use an epoxy. It is more waterproof. Vinylester is used for handmade gas tanks, but it's because modern gasoline attacks epoxy.

Please don't try to save a few bucks using polyester resin for boat repairs. You will very likely be sorry later! This is penny wise and pound foolish.

Polyester may be fine for new construction, but for repairs to existing construction you need the "secondary bonding" capability of epoxy. Like Ebb said, epoxy is an adhesive resin, while polyester is not.

Polyester works well only with primary bonds--that is, the chemical bond that forms when layers are added within the "green" working time. Once this brief window of opportunity has passed, the bonds will not be particularly strong. The same goes (especially) for bonding wooden pieces with polyester--wood and polyester do NOT like to stick together for any length of time.

No one ever said boat repairs were cheap. You still have to use the right product for the job. For most boat repairs, the right resin is epoxy. It doesn't have to be West System--many of the other epoxies are also excellent. Each system has its own unique qualities, strengths and weaknesses, however, and each is slightly different to work with. West System is an excellent epoxy, but my no means the only one out there. Amine blush is, to my way of thinking, an extremely minor thing to worry about--it's very simple to scrub with water and Scotchbrite pad, and once it's a habit you don't even think twice about it.

Unless you are laminating on green resin of any kind, you are getting only a secondary bond. Once the green stage is passed, you need to choose the product that will give you the strongest mechanical, or secondary (adhesive) bond.

Don't mess with this. There is a difference between poly and epoxy, and it's a very important one for this application.

Personally, I didn't like MAS epoxies when I tried them--I had trouble with incomplete curing, among other things. I have never experienced a single problem with West System--it always works exactly as intended. Also try System 3 or Raka. Buying the small cannisters of West System filler products will break your budget in a hurry--you can buy any filler in bulk from Raka or System 3. They are the same thing, and also work with polyester (not that you should be using poly!)

Tim

For one thing , it's not polyester resin anymore , it's vinylester resin , it looks and smells like poly and uses the same hardener.
You can still get poly , but why would you . Even Gougeon admits that vinylester is more waterproof than epoxy .
I have worked with the 'esters' for 40 years now .
Epoxy is no better than poly , as beer is no better than wine .
The library is full of books about poly resin construction .
There are at least 5 varieties of the poly group with vinylester at the top , the $15 a gallon poly at the bottom .
Epoxies are so divided by hardner ratios , from 1:1 to 1:7 . 1:1 is the cheapest and least toxic , 1:7 the priciest and most toxic . Strength and waterproofness varies greatly (the most waterproof is not always the best or what you need ) . Almost all brands of epoxy use the same basic resin , it is the hardners that make the difference .

Good workable epoxy & poly can be purchased from;

fgci.com

I pay $65 fo 2 gallons of 1:1 , for a barrier coat you want 1:3 to 1:5 . 1:1 is fine for laminating , sheathing a wood boat with glass or interior and deck work .

There is nothing wrong with WEST System except the price , it is like CocaCola ,marketing and name recognition .

With epoxy you can get real bad dermatitis and some lung disease .
I am living proof of what can happen from long exposure to 'poly', 2 bouts of chemical blood poisoning , the last nearly killed me .

A good ( $$$ ) respirator is necessary and always work out doors or if you are in the cabin with 2 fans , one in & one out .

Tim,

I covered a dinghy with poly and glass , it lasted for 21 years of constant exposure to the southern sun & saltwater .It may have lasted longer , but was brought to an abrupt end when a trawler pinched it between itself and a dock .
Poly is not a glue and should not be used as such , but as a laminating layer is is equal to epoxy , now that epoxied boats have been around for 25 years people see that it is not the panacea we thought it was in the late 70's . Good boatbuilders and repair yards use both .
Epoxy has one fault that poly doesn't suffer , thermal breakdown when used topsides under dark colors .

Great cautionarys here from guys who have used this stuff. One more bit from ebb on epoxy. I have not used West System. The reason is that the System uses cheap carcingenic extenders. (nonyl phenol - MDA) These extenders cause the blushes. A blush is a WAXy film. These extenders cause cancer. OK? Why put up with washing your work when you can buy a better product?

The epoxy you use should ONLY have a FAINT toasty smell (from the amines) I too became allergic years ago to the amines where it attacked the fingers at the nails. Gee! I learned to use latex gloves.

The key words for epoxy is:

100% solids.

If it don't say that it's not good, No matter who told you or how well you have aclimatized your poor self to some corporation's (profit) system. Really! DO NOT USE IT, even if it's made by cocacoli.

If you had epoxy shipped to you and they had to hazmat, you bought the wrong stuff. See ya! (hope so)

i found the website. oddly enough it was buried inside an article about building tanks for sanitation.

http://www.boatus.com/goodoldboat/sanitation.htm
you have to scroll down a bit, but there is a side bar by an ER doc about poly/epoxy, safety and chemistry.

but i plan on using epoxy when repairing any hull dings during my hull refurb.

-km
Hull#3

With 3-M vinylester putty , you can be sanding those ding repairs in less than 15 minutes of application . That is what most pro marine paint shops use . You can use epoxy if you want and you can marinate hamburgers with a $300 bottle of Merlot if you really want to . I'd save if for sipping with my lady .

Not quite sure if this is worth the time here but....
Doc Parker in mrgnstrn's ref gets his info on the epoxy he talks about from who? Gougeon Bros. He briefly says "epoxy dust is toxic if inhaled."
As a reader of this your only assumption can be: it's Gougeon Bros epoxy dust that is toxic. Right?
First off: the good doc presents no evidence for this statement, and it is therefor, hearsay.
Second: inhaling any dust (while it might not be exactly toxic) is bad for your lungs - you should always wear a dust mask when sanding or grinding, even the fuzz off a peach.
Third: if epoxy when cured is great for potable water and all manner of food containment, what is toxic? If the good doc's info comes from Gougeon Bros - who do use 'toxics' in their epoxy formulas- don't use Gougeon Bros epoxy for your water tanks. THAT IS THE MESSAGE.
Fourth: beware of advice from masked men in blue pajamas.

Paul Oman's epoxyproducts site is IMCO the premier source for info the subject. There's just the right formulation of non-toxic erascibility, honesty, and intellect for unpredjudiced information. In the past he has returned email questions of mine. It's a good site. IMCO

As far as I'm concerned, all of this stuff should be treated as toxic.

Acetone is probably the worst. It eats through regular gloves and makes your eyes water even with a respirator on. Must be real bad.

I'm curious about Dr. Mark's statement that poly adheres better to poly than epoxy does. I'm not so sure about that.

From the latest BoatUS flyer

Yeach, I think it's this guy what has a project book published that uses polyester for everything inside and out on an existing boat.

You can do it to save money (blub blub blub) and to assure adhesion you have to grind with 36 grit (gee, 24 and maybe 16 grit will be even better!)

The cheapskate drowned and/or the grinder died from polyesterosis.

What he describes in the first paragraph for polyester is even more true for an epoxy 'lay-up.' You can get yer bloody 'chemical bond' just as easy, in fact much more easy and safely, with 100% solids epoxy. Just put one layer on top of the other, wet it out with epoxy - wow, and no waxey top coat. Epoxy you probably should create some tooth between layers if it sets up. That's right, but you don't need to grind.

Use Epoxy. Use the best epoxy you can get. At least Mr C. sort of implys there is a guarantee with the pricey stuff. But you'll always be wondering about the cheap stuff. IMCO


Years ago a planked 8 X 29' gaff rig sailboat I had was glassed with cloth & polyester. I must have let it go overnight or maybe even days between layers. It never failed so far as I know. So I will defer to the experts here - I don't know modern polyesters - as long as you don't put the finsh coat on you can come back to it later. How much later I don't know. The project is 'wet.' With epoxy, you can repair things, smooth and fillet, cut and shape, come back and add more layers. Much more versatile and forgiving.

While working on my dingy Sunday, I came upon a particularly difficult substance to remove. I was coating a piece of ply in epoxy and mounting it to the transom for the motor, and there was a 'goo' that acetone would not remove.

I went to MEK, that I found in a rusty can in the flam locker, and it worked.

I remember years ago, that I had decided MEK was a substance I would no longer use, (something about being absorbed through the skin and there being no means for the body to excrete it) so I went online this morning to refresh my memory.

Came upon an unrelated piece of information about MEKP

Methyl Ethyl Ketone Peroxide that is used to cure polyester.

Apparently, if it is exposed to acetone, the results can be drastic. Kinda scary considering the two chemicals are regularly used, and stored together.

:eek: :eek: :eek:

Note to self. Don't store poly catalyst and acetone together.


Here is where I found this, fwiw
Link to discussion of hazzards of MEKP



Any thoughts Ebb?....

mornin' Craig,
Just scrolled down to yer recent post,
ah shure am a curmudgeony s.o.b!

MAKES POLYESTER A PRETTY LETHAL COCKTAIL doesn't it?
Yet I know I could get into somebody's face about it and they'd still edit out what they don't want to hear! Including them who publish advice. I don't mean, 'wear gloves and a mask.'

It's a little late now to find out, but those nameless Azorian farmers who pasted our fleet together, I wonder how their health was after their return home? I'm sure some safety protocols were enforced at the factory in the 60s, couldn't have been very sophisticated. Just guessing.

Once I practically bathed in polyester. Stoned myself on the saccharin fumes. I was born stupid. And I may not have recovered yet, and, as you point out, may never will. :(

Your health is only as good as you can afford.
You can afford good epoxy.

* If in this case the 'sword' is polyester, then the dance is a positive airflow mask, tyvec suits, nitril gloves and a good plan of action based on practice. On the estate here the guys working with face shields or dust masks on a task will remove them as soon as the heat leaves - because it ain't macho to wear them, I presume.

Once one decides which barrier and anti-fouling paint to go with below the waterline how does one apply it around the "pads", if that's what they're called, that are holding the boat upright in the yard? The guy at Interlux said "just move 'em" - but then what? - put the pad elsewhere on wet barrier or paint??

A. Paint the blanks out when yer in the slings. And the bottom of the keel too.
B. Get the harbor master to reposition the jacks, wax paper the pads.

You paint around the pads , let it dry ( barrier coat or antifouling ) the get the yard folks to move the stands for you , or at least ask them if you can do it . Doing it on your own can void their insurance and get you tossed out of the yard .
I've seen idiots take out all the stands under one side of the boat to paint there , while wife and kids were roaming around topsides . Travellift was promptly dispached to get them out of the yard ( half painted ) !!

Hullo Brendan Watson??? Still there?

To answer your original question,
there are two non-technical (in the old sense) fiberglass books published in the '60's that parallel the age of our A/Cs. One is Allan Viatses' FIBERGLASS REPAIR MANUEL. He also virtually invented the method for sheathing wood with polyester. You really don't need a more technical manual than this in the use of fiberglass.

And certainly the friendliest of all is the wonderful classic: FIBERGLASS BOATS, by Hugo du Plessis. You shouldn't have any trouble finding these. Later editions are updated.

With these two manuals you'll have a lot of know how. My early editions of these books mention dermatitis as a problem for some. And if you develop the problem 'stick to wooden boats'! So there is a golden light of innocence pervading these adventurous how to do it source books. Maybe not right in light of what we now know about these chemicals - but a relief! Can see how I just dove right in.

These really are the polyester classics. Specific epoxy manuals and tip sheets are found at West System, System Three, etc. But the principles are basically the same.

Smith & Co.'s ALL WOOD GLUE, so far as I know THE best epoxy wood adhesive on the market, has a label on the can 1/3 of which in small print spells out hazards, a 'non warranty' in lawyereze, and ends with: 'This product is inherently unsafe - It cannot be made safe.' There should be a skull and bones on all this stuff. But this is a dangerous world and testosterone (AND the profit motive) rules.

As I have worked my way forward, I have faired where necessary and when that was not required I have simply filled the crazing with pure epoxy.

One area that was required no real fairing was the cabintop.

Not too pretty to look, (I actually raced it like this) :eek:

The hatch was removed again, and another coat of epoxy smothed over the surface. Primer, and a couple coats of topcoat later.....

Polyester vs epoxy is covered here pretty well. Leave polyester behind for the moment.
Epoxy coatings are a huge segment of the industry, with the use of epoxy for DIY composite
construction a distant second or third.
Why one epoxy is somehow better than another's hasn't been explored. Repair & remodeling
interest is aimed mostly at laminating, predominantly glass, and various other core materials
of wood and sheet plastic with 2-part resin... to create strong continuous molded composites
of every imaginable form including the boat itself. But includes also various powders, milled
and chopped strand added to resin for powerful structural moulded parts & repairs - and can,
slightly thinned, be used as a 'penetrating' sealer for wood befor varnishing or painting.
Epoxy resin is generally easier to use, safer, stronger, more waterproof, makes a superior
adhesive -- it is incredibly versatile. What makes one brand epoxy better than another? ....
THANKS FOR THE INSIGHT from this professional user of epoxy.....

Here is the quote extracted like a tooth out of a solid jaw of type
from a surfboard site written in March 2003. So it sort of fits the time period of this thread.
And ebb's as well ....because my prejudices come from that period also.
Again, reviewed GougeonBrothers' WEST SYSTEM Brand MSDS on its main formula 105
laminating epoxy and hardeners: 205etc. Ingredients seem not to have changed in 20yrs.

http://www.seabase.eu/docs/epoxy_safety
SO, I hope it is OK to pry a few sentences from the text: Epoxy is not a carcinogen.....

"What epoxy is , is a skin sensitizer. This varies greatly between different epoxy systems
depending on different company's formulations. Most older epoxy hardeners are formulated
with a chemical known as TETA or another called DETA. These base hardeners are in the
aliphatic amine family, are very reactive, somewhat unstable, quite toxic and easily cause
sensitization of the skin (or dermatitis). Most of these hardeners are also modified with
phenol and formaldehyde. Phenol is what dermatologist use for chemicak skin peels and
increases TETA and DETA's toxicity to the skin dramatically. Many of these older hardeners
are up to 50% phenol. Formaldehyde is also no picnic as it also increases risk because
of its ability to act as a vehicle for the phenol and amines through the skin and into the blood
system. By the way, the reason why these epoxy hardeners are still used today is because
they're CHEAP. DETA and TETA cost 1/5 what a modern diamine based hardener costs to
produce. Anyone who has worked with many of the WestSystem epoxies will be familiar with
these low cost systems. Modern epoxy hardeners are nothing like their 60's counterparts.
They are formulated with modern diamines and have vastly reduced incidences of sensitization.
They also have lower vapor, better color, better finish, and lower exotherm. They contain NO
phenol and NO formaldehyde."

DETA Diethylenetriamine. TETA Triethylenetetramine. (also TEPA Tetraethylenepentamine)
There is a WestSystem mission statement that proudly admits that Dow is the progenitor of
their epoxy formulas. They DO contain phenols and DO contain formaldehyde. Even in 2014.
Being married to Dow may be good reason why WS laminating formulas are still composed
of toxics, solvents, cheap chemicals... and blush amine to prove it (possibly in embarrassment.)
Ample evidence that WestSystem has NOT upgraded to safer epoxies for their DIY customers.
(While amines and phenols are not known to cause cancer, they are considered moderately
toxic. FDA considers formaldehyde a carcinogen, and it causes chronic neurological conditions.)

..............................WEST SYSTEM EPOXY --- WE ARE DOW.......................................

Buy laminating resins from user-friendly companies who offer 100% solids epoxy.

.................................................. .................................................. ....................................
{OK, for brevity: Here are three phrases in heavy caps printed on the large lid of a bulk kg
container of the latest green powder superfood I'm drinking: ......(food for thought)
TRUTH TRUST TRANSPARENCY * FULL DISCLOSURE LABEL * NO PROPRIETARY BLENDS
Begs the question: What's on our brand name epoxy labels?}
.................................................. .................................................. ....................................
To my knowledge no third party tests have been conducted comparing tensile strength and
adhesive properties of West System Brand with other brands.

Ingredients in Side A 105 are graded mildly hazardous and low toxicity. As much as 30% of
the formula is Benzyl alcohol, Phenylmethanol. This solvent is considered hazardous when
there is 'overexposure' - as one might expect.
Bisphenol A is an epoxy monomer made with acetone & phenols. It's found in nearly every
epoxy MSDS. BisA has been identified as an endocrine disruptor.
It combines at will with human sex hormones by mimicking them.
We won't find this bon-mot in any MSDS. After all, it's not cancer. Just sex change.
It is a problem that regulating agencies do not want to handle, probably because the
compound is too pervasive in the plastics industry to control. Therefor it's dubbed 'moderately
toxic' - 'skin sensitizer' and 'low acute oral toxicity'. Corporations rule.
.................................................. .................................................. ....................................
Epoxy - allergic reactions
This thread can be found on pg5 in the Technical forum Archive
OR type into google: title +pearsonariel.org

also: resin & glass info 2-22-2015 --General/Off-topic forum
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~

EDIT
pauloman's epoxyproducts.com website is an experience you can't miss. For some, like me,
it's difficult to navigate. It's a riot of color, continual shouting headlines and big print. There's
all kinds of signs, like a labyrinth, that beg you to go off subject, so staying focused is the
only way to win. BUT it has the most complete information on epoxy you'll ever find.

It was here I found the original revelation of the toxicity of West System laminating epoxy.
As of July 2016, can't find it anymore. But the actual MSDS, still available on the Gorgeon
Bros site, tells the hazards of the DowChemical formula that these people foist on amateurs,
promoted by WetsMarine as your first and best choice.
Epoxyproducts sells mostly epoxy. In my opinion, I can find no 'page' on the site that collects
all cautions that should be evident, or featured, that explain just what the hazards (and
physical limitations) are when using any epoxy product.
Here is what he is saying (loosely quoted) about N-P, 'nonyl-phenol, a chemical additive in
almost all epoxies, is added to adjust A & B parts to aid in making them easy to precisely
measure. 1 to 1, 2 to 1, 4 to 1.
(Epoxyproducts talks about its good and bad properties, admits to also selling some epoxy
containing N-P) In cheap epoxies it is a "water down additive that reduces physical
properties of epoxy." It requires hazmat for shipping, it has health risks.... But most
important for us, it retards the drying of oil based enamels applied over epoxy containing
nonyl-phenol, especially in high humidity.' Raises human stress levels.
From this I can see how Epifanes (altho not sure if all their coatings are oil based) insist
that a special primer must be used over epoxy before their paints can be applied on epoxy.
Humidity is the key word in the waxy blush that epoxies like WetsSystem throw. From this
conclude that 'cheap epoxies' formulated with nonyl-phenol can screw up any later work
-- even if you wash it off (with soap and water -- solvents don't work on this wax)
Therefor the PRIMER thing insisted on by one international paint co.

Suggest that NOTHING is going to stick to wax, except dirt. Just guessing that it has
something to do with cheap epoxy 'throwing' garbage on its surface when setting -- and
tying that to nonyl-phenol tainted epoxy 'retarding' enamels -- maybe it's the same failure.
Could it be the evil twin of silicone oil??