Epoxy and Vinylester Resin

I am applying fiberglass on the bottom of my new boat (wood construction) and have finished one coat of E oz E-Glass with vinylester resin. However, after much research and the difficulty it is in canada to get vinylester resins, I would like to switch to the system three laminating epoxy resin and a second coat of E-glass. Has anyone done this before, mix vinylester and epoxy resins on top of each other over an entire surface? Does the surface between form a strong enough bond? I have tried to find the answer to this question but no concrete advise yet. Thanks for the help.

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RE: Epoxy and Vinylester Resin

System 3 will bond to a lot of things as long as the surface is roughed up, although I have not tried it on vinylester resin.  You may not get any concrete answeres becuase it can be very hard to predict results when mixing brands.  One option is to do a test.  Laminate glass to scrap plywood using your initial resin. Let dry then sand the surface to give the next layer some "bite".  Next laminate more cloth to the surface using system 3 on top of the resin leaving a legth of cloth saturated with system 3 overhanging the wood.  Once dry use some vicegrips on the overhanging cloth and pull HARD.  If it bonds properly the plywood should delaminate and fall apart before the cloth lets go of the original resin.

RE: Epoxy and Vinylester Resin

steele's test needs a little tweaking to be meaningful. First, before doing the pull test, it's vital that both layers have time to fully cure. The vinylester layer must be fully cured before the epoxy layer is applied, and the epoxy layer must be fully cured before the pull test. This is because the epoxy/vinylester bond is going to be mechanical, not chemical. I'd let the test piece cure for at least a week inberween phases, possibly under a lamp if the temperatures weren't constantly above the high 70's before performing the test.

Next, the peel strength of a lay-up (which is all this tests) is not necessarily the most important quality. For small boats, the tensile strength and abrasion resistance is usually much more important. I'd say that even if the glass peels off, as long as it took real effort to make it peel the bond will be good enough. I also think that no matter how strong the bond, it's unlikely that a peel test will make the plywood delaminate (unless it's really sorry plywood, like doorskins or luan). What's much more likely to happen is that the glass will fail right where it's being gripped by the pliers and the pliers will go flying backwards banging into some body part, causing great pain.

Finally, for small-scale tests such as this, System 3 sells a test kit which is much cheaper than having to buy a larger quantity. For that matter, they also have a reall good tech support department who can probably answer this question with no guesswork.

Good luck,



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