Vinylester vs Epoxy

[comfisherman]

Nice, that's a product I'll have to try. We did a fish hold repair on some questionable foam with epoxy. The rest of hold is gel coat white and the owner wasn't super stocked on having to paint part and have gel coat on the rest.

 

[silentneko]

I'll look into it. Thanks.

 

[starcmr]

Looking at my next project hull and considering my resin choices. I'm not 100% on what core I will use just yet, but I need to nail down the resin type so I can start repairing the hull. For reference the hull was built with polyester in the late 80's.

So I can get both VE and Epoxy at a similar price per gallon, so cost isn't the issue. I've used mostly Epoxy the last decade or so Snptube, and some polyester before that, but never done much with vinylester. So my pros and cons

Epoxy;
Pros:
- easy to mix
- waterproof
- very forgiving on time
- strongest resin (marginally?)
- no wax or coatings needed to cure
- very little fumes or smell
Cons:
- must sand between fully cured layers
- blush is possible
- allergic reactions experienced by some
- must be painted as gelcoat won't stick well

Vinylester;
Pros:
- Strong
- highly water resistant
- any paint or gelcoat will work
- no sanding in between layers of work (within reason)
Cons:
- fumes or smell
- must use a wax, coating, or modifier to cure
- must adjust MEKP for different temps

Am I missing anything? Thoughts? Preferences?

Since the hull was built with polyester, vinylester is the better choice for compatibility, adhesion, and gelcoat application. It’s strong, highly water-resistant, and allows for layering without sanding. Epoxy offers the best strength and waterproofing but requires extra prep for gelcoat and sanding between cured layers. If gelcoat is a factor, go with vinylester; if you prioritize strength and don’t mind extra work, epoxy is a solid option.

 

[sailhand]

Been building boats since 1996. Mainly big catamarans. Used many techniques including resin infusion vacuum bagging etc. 15 odd years of epoxy, mainly west system, before allergic reaction pushed me very reluctantly to the esters. Recently been using low allergy epoxy again without problems, so far!! The ester build process seems much much faster to me now. Price is way better in Australia for the esters compared to epoxy and foam core is cheaper now than good quality ply and rot free. cheaper ply is available if you wish to use it.
The build process with the esters when unwaxed is much quicker and easier in my experience. Just little things like no sanding between laminations and the ability to mix bulk fillers all at once. After using epoxy in recent weeks the need to mix powders every single time you need to use them is a pain. Fillers blowing everywhere and the slow time consuming repetitive mixing is terrible. With vinylester I mix one 20 litre tub of fillet mix and one 20 litre pail of fairing compound with a large power mixer super fast and easy. Then if I need to do a fillet I just grab some mix, easily add catalyst with no dust or endless mixing and no sanding of laminates. Wax in final fairing compound with the same easy premixed arrangement and again no sanding before bogging. No peel ply, way less sanding with savings in sandpaper cost and labour, less dust in the work environment.
I don't think I'll be using epoxy again unless I have too.
Just on the gelcoat over epoxy issue even the gougen brothers own testing proved it to be a successful technique for finishing epoxy laminates. I did a job with polyester flowcoat over west system epoxy twenty years ago and it's still in perfect condition. Good prep is the key to successful boatbuilding with fiberglass.
So in summary for me, cheaper, easier, faster, safer with less dust and most importantly no labour, sandpaper and time to make that dust. One caveat here. I live and work in a sub tropical climate and work under shed roofs with little or no walls. Ventilation is as good as it gets. Some guys have problems with ester fumes and cooler climates with enclosed work environments would definitely compound the problem. Good luck with whatever you choose. Cheers

 

[wet feet]

I totally agree with the previous post.A few months ago we had another thread about wax and resin and a couple of us mentioned that adding wax is hardly ever done with esters,the mix being good to use as supplied.The fumes do seem to put off a number of people and if that aspect is a problem then adding a fan to extract the styrene isn't difficult and it helps if the pickup point can be adjusted to be close to the lowest part of the component being worked on.The widespread enthusiasm for epoxy among hobbyists may be due to the amount of advertising in the recreational boating sphere and an amount of insecurity if they mention in company that they didn't use the "ultimate" laminating resin.There is vastly more polyester holding boats together around the world than there is epoxy and is is causing a few problems with sixty year old boats failing to deteriorate and needing to be demolished after a few decades of neglect.There are situations where the ultimate weight saving techniques are justified and the combination of design and materials will need to be carefully considered.Most displacement boats aren't in that category.

 

[silentneko]

Ok guys, I've been giving it a lot of thought and I think it's going to come down to really one aspect, off gassing.
Several have mentioned the VE having a strong smell, possibly worse then PE. I've really only used it in small quantities in the past so it wasn't bad, but this will be a bigger project.

Keeping in mind this isn't in my garage, but a rented warehouse that I am in close quarters with neighbors as the bays are only 10-12ft wide. I don't want to be discourteous to the guys working on stuff around me (cabinet makers, car guys....), so if the fumes are really that bad then I think I'd better stick with epoxy.