Vinyl Ester vs. Epoxy Technique

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#1

Is the technique pretty similar when doing a layup with vinyl ester as compared to epoxy? There is a ton of info for epoxy laminates but I searched and couldn’t find a good procedure for vinyl ester. I will be doing a wet layup vacuum bag with a HC core so can I just follow the same basic techniques of brushing on a first layer, letting it tac, wet out the first layer of CF etc.?

The plugs are almost done and I’m getting close to making the molds and parts which is exciting. I think I would be close to lost without this forum. :smiley:

#2

Yes, resins would be the same procedures. Of course, make sure you are in the guidelines of the gel time!! VER just smells a LOT worse.

#3

Great, that is what I thought. I am using Derakane Momentum 411-350. The gel table has some times and mix ratios. Are these the gel times if it were a larger qauntity in the cup? Will the thin film gel time be longer just like epoxy?

Derakane Momentum 411-350

#4

with my experience with gel times of Derakane’s VERs (510 and 411-530), large masses in RT water baths have a slightly shorter gel time. I’ve also noticed that our 510a, which we go through faster is spot on, while the 411-530 is shorter…but it’s also a few years old. Do a test yourself, see what happens, or just add a lot longer gel time.

#5

Keep in mind that the geltimes given are just guidelines, and can vary from batch to batch. Also viscosity and rheology can vary.

The times given usually are in 100 gram cups, so a relative large mass. Thin film times are longer.

Also keep in mind that thin vinylester (like in a thin coating) can refuse to cure, even when the right amount of catalyst and initiator are added. But when you do thicker coatings (gelcoat) or laminates you should be OK.

Another thing to watch is that epoxy has a lot slowe cure. It first starts to thicken up, then becomes syrup, then a paste-like consistency, then becomes solid. Vinylester does the same, but the time from slightly thickening up to solid is much shorter. If you want to vacuum bag, if you see the resin thicken up, basicly you are too late. With epoxy you still have time to apply a vacuum bag.
What to do: From your first batch, save a bit in a 100 gram cup and set it apart. As soon as that cures, it is time to bag. (same works for epoxy)

Also make sure your catalyst (peroxide) is of a sufficiently slow type. You can even add a retarder if neccesary.

#6

Thanks guys, that’s exactly the info I was looking for. It will be a big help :slight_smile: