Epoxy and Vinylester Toxicity

A lot of builders of composite quality canoes use vinylester resins for a several reasons.

First and foremost, it is cheaper than epoxy. Good vinylester resins are now almost as strong as epoxy and Dave Curtis once told me that some military-grade vinylester resins are actually stronger than epoxy, but I don't know that those are used by boat builders.

Vinylester resins can be less viscous than epoxies which is a boon for vacuum bagging and especially for infusion processes. The cure time for vinylester (and polyester) resins can also be adjusted by varying the amount of catalyst added to the resin. Epoxy resin and hardener must be mixed in a relatively precise ratio which cannot be varied, although different hardeners that cure at different rates are usually available.

Vinylester resin has a finite shelf life, which is a major reason I don't use it for canoe repairs. The limited shelf life is not a concern for builders who are laying up canoes on a regular basis and using it up continuously, however.

Thank you for the welcome Glenn.

@billconner my understanding is that builders can become “sensitized” to (I think only uncured) epoxy and develop up to severe reactions. I have not seen anything saying that this can happen after curing, but I’m not sure to be honest and would like to find out…curious if anyone knows?

At this point the chemical makeup of epoxy seems to be more of the reproductive harm variety, while vinylester seems to be that, as well as carcinogenic.

On the flip side the raw ingredients for epoxy seem to be more toxic to aquatic life with vinylester having more of a moderate aquatic toxicity. It does seem some leaching occurs, to what extent these toxic ingredients are locked up and what changes occur in the final product after curing, I am not sure.

Unfortunately, not great either way I’d say.

I know a guy, an amateur boat builder, who has developed a severe allergy to epoxy (or maybe hardeners?) and can only work with polyester. I'll ask him whether this includes liquid epoxy only or whether he mustn't touch also cured epoxy.

Glenn MacGrady: Thank you for your greetings.

." It does seem some leaching occurs, to what extent these toxic ingredients are locked up and what changes occur in the final product after curing, I am not sure."

We worry leaching, including of uncured polymer, in things that touch patients or contact drugs.

You might want to consider the other parts of the composite. The kevlar, carbon fiber, or polyester cloth will be a major contributor to the chemical profile. Maybe just as important as the resin. I have no idea about these fibers, but I would expect they include lots of plasticizers.

I would focus greatest attention on what you touch, like the gunwales. I have no idea about the coatings on aluminum gunwales or wooden gunwales.

One can indeed build up a sensitivity to epoxy. I am close to the tipping point I think. I have to be very very careful now to make sure none of the liquid or semi hardened epoxy touches me. My lips go numb first, and then my skin flushes. Sometimes itching too.

I'm at 30 plus canoes, i think I only have one or two left in me. When I was young and bulletproof, I was not very careful with the use of epoxy, and I should have been. Also, I believe I read in a System Three pamphlet that a full cure is needed before sanding, as when the epoxy is still green, it is indeed carcinogenic. However, completely cured epoxy is supposed to be inert.

So far, system three silvertip seems to be the least reactive to me, I didn't get numb lips once in my last application.

@memaquay - sorry to hear that! No negative reaction to fully cured product, however?

Please use a respirator for sanding all forms of resin. It is hard on the lungs and it is easy to develop allergies to it.

No negative reactions once fully cured, so that is good. Even spar varnish is starting to set me off now.

Jabberwocky said:

I know a guy, an amateur boat builder, who has developed a severe allergy to epoxy (or maybe hardeners?) and can only work with polyester. I'll ask him whether this includes liquid epoxy only or whether he mustn't touch also cured epoxy.

Click to expand...

So here's the answer. He's allergic to all kinds of epoxy but he suspects hardeners. Both (even fleeting) skin contact and breathing in whatever amount of vapours is a problem. All of it results into a rash, blistering, skin dryness and cracking and the symptoms usually last for a month. Corticoid ointments help. The trouble started some 30 years ago after a massive laminating event that included a full barrel of epoxy resin. Doctors warn him not to push his luck as the body can develop the allergic reaction also on inner organs, not just skin. That's already a life-threatening condition. Really old cured epoxy is ok, but the newer the bigger the risk, also with products that are considered cured. Scary stuff. Polyester, on the other hand, is completely safe for him.

To add my two cents pence hellers, I cannot tolerate any of the fumes for long, whatever the resin, as they cause me severe headaches.