Epoxy vs Vinylester
 

In a critical structural application does epoxy hold a clear edge in the category of adhesion?

The application - Construction of an integral bracket which will tie into the existing transom, stringers, and interior hull surfaces.

Let us stipulate for the sake of argument that the resins are properly prepared, the fabric being used is appropriate for the job, the existing structure is fully cured and sound (polyester), and adequate and correct prep work is done prior to application.

Re: Epoxy vs Vinylester
 

I'd vote for epoxy, have used both and it always seems that the accidental drops of epoxy are stuck to whatever they land on better than vinylester, ie you can usually chip a stray drop of vinyester off & it'll come off cleanly, not so with epoxy it usually takes a layer of whatever it landed on with it.
Lots of good scientific data on the web that back up epoxy when fixing or adding to an existing cured structure.

Re: Epoxy vs Vinylester
 

I am interested to hear what others say.

My impression was that you can can poly on top of poly, or epoxy on top of poly, but you cannot add poly on top of epoxy (no chemical bond).

I use the basic no blush epoxy from the new hampshire guy with the crazy website, but have been thinking about using poly or vinylester.

Re: Epoxy vs Vinylester
 

I haven't used vinyl ester, but I have used epoxy so I'll add to the anecdotal data. I forgot to clean up a ribbed aluminum roller after an epoxy layup and found it stuck to the deck the next day. When I pulled it off, it took a neat chunk of the gelcoat with it. So the epoxy's secondary bond was stronger than the gelcoat's (presumably) primary bond.

I've been buying my epoxy from US Composites. Their epoxy is at about the same cost as their vinyl ester @ $45/gallon, so for me it's a no-brainer.

Dave

Re: Epoxy vs Vinylester
 

for secondary bonding, there is no compsrision. Epoxy is far superior in secondary bonds.

Re: Epoxy vs Vinylester
 

I think you are on track there. From what I can gather, while epoxy will cure just fine over poly (and bond aggressively), the chemical makeup of epoxy actually inhibits the curing process of poly and vinyl resins. The lack of bond is due to the fact that the newly applied poly/vinyl resin never fully and properly cures at the interface of the two materials.

Re: Epoxy vs Vinylester
 

I had noticed they seemed to be much cheaper than some of their competitors, but wondered if it was because they were selling a significantly inferior product. You've had good luck with it?

Re: Epoxy vs Vinylester
 

I got basic no blush epoxy from Progressive Epoxy in NH. With the ... dense website. Lack of marketing results in lower prices... for a superior product. Unlike west, there is no amine blush or wax removing step.

Another question: faring compound. Use the pre-mixed stuff (quick fair) or make your own?

Re: Epoxy vs Vinylester
 

I've used US Composites on a hard-top restoration and I'm now using it in a transom re-core and have had NO issues with it. As far as I'm concerned its a very good product and competitively priced!

Re: Epoxy vs Vinylester
 

Good products. Good prices. The only things I can get cheaper locally are polyester resin and glass cloth. And that's because they are both basically commodities and the cost difference is the added shipping.
Dave

Re: Epoxy vs Vinylester
 

I agree with all the above. Epoxy is alittle stronger. But you have to think these boats are polyester and the glass on mine is still in very good shape. It has held up 34years so far. I would definatly use epoxy on a bracket though.

Kenb.. I have used about 1.5-2 gal. of qiuckfair and I am very pleased with it. Just get a digital scale to measure it out with. I have also used west sytems 407 and 410 fairing filler and they are also good. So for a large surface I would use quickfair.

Re: Epoxy vs Vinylester
 

Just my 2 cents but I've used both and I'd stick with poly or vinylester. Epoxy is strong but annoying to work with, try laying something up on a vertical serfice lol, good luck.
Remember, these boats are all made with poly and are stong and solid as hell. You not going to reinvent the the wheel by using epoxy.
Btw, I have gallons of system 3 if anyone wants it...yuk!

Re: Epoxy vs Vinylester
 

I will take you up on this offer. I could use some epoxy to make my fishbox. Give me a call to set up shipping 252-342-2509 Thanks

Re: Epoxy vs Vinylester
 

poly & vinylester are fine on a new build, when laminating wet on wet layers of material, but you'll never get as good of a bond onto something thats already cured. Thats where epoxy has such an advantage, a great secondary bond. It's also easier to mix, doesn't smell as bad, & has a longer working time. But you can't put gelcoat on top of epoxy.

Hey Dave based on the speed you are working at I would be more concerned with which product has the longest shelf life :D

befor starting my rehab on my 20 SF i went round and round trying to find out which is realy the best to go with and in the end i used poly, the price was realy the deciding factor for me. im sure the epoxy is a better product but in the end but i kept being told it would be good for a liftime.... but i hope its not my last boat so if its good for another 10 plus years thats ok with me. as for molding in a bracket that is using no fasteners i would go epoxy.

Vinylester and polyester aren't the same thing. I had it explained to me that it can be thought of as similar to a polyester at one end, and similar to an epoxy at the other end of the chain. With properties in between.

My one class in composites was back in the 1990's so take it with a grain of salt. I do know that the curing agent is more like polyester.

I used vinylester last year, and it sticks to polyester and epoxy. I used it as a primer coat between epoxy and a polyester gel coat, and it is tenacious. I hear it is often used as a barrier coat on epoxy sailboats.

I like it enough that I want to use it more. It is safer than epoxy from a sensitization standpoint, higher performance than polyester, and compatible with either.

Nitrile gloves. Nice properties.

I have herd that the epoxy is more flexible than the poly but was wanting to know if done right will the poly hold up to a lot of flexing. Don't want to have stress cracks develop if the boat is getting a lot of pounding in a ruff water conditions being ran hard. The poly I can order a 55 gal barrel for $975 and the epoxy is over $2700. Also I have herd that poly has a shelf life of only a year or so. That worries me on getting the 55 gals. Will it last longer if it is in a controlled environment and if so what temp dose it need to be stored at?