Question about poly resin

[SweeperForce]

I have a question about the differace in polyester resin. I saw an online vendor selling 404 tooling resin for around $40 per gallon. The problem with an online purchase is shipping charge and haz-mat fee. I also found at Home Depot poly resin made by Bondo for a lot cheaper. The base cost of the resin is the same but no shipping and haz mat fee. Is all polyester resin the same or are there different grades or qualities?
Thanks,
Tom

 

[jbcurt00]

HD resin likely has wax in it, you want laminating resin

HD resin may not be 'fresh' esp the MEKP

 

[nurseman]

^^^ what jb said. Bondo resin will have wax, which means that every lay up will need to be sanded before you can lay over it. Also, the shelf life of MEKP is about 3 months give or take. If you buy HD resin, you might want to do a small test batch to make sure the MEKP still kicks off. I tend to reserve the Bondo resin for making filler, or other non structural things, but that's just my 2 cents worth.

 

[Woodonglass]

SF, what are you Glassin? All the retail outlet "Bondo" brand resins have wax. This is not necessarily a BAD thing as long as you can apply the next layer of glass before the previous one cures. Like Nurseman says, If it does then you'll have to sand and wipe down with Acetone and even then it can have bonding issues. And as everyone has stated, ALL Poly resin has a shelf life as does the MEKP and the retail stores can keep stuff longer than they should. I totally understand the Online prices can be high due to Hazmat fees etc but using the right product is the best way to go.

 

[SweeperForce]

Thanks for all the advice. I found some good lay up resin great for laminating and no wax. What are your thought about vinyl ester resin? I read it provides a strong bond and is very stiff. I plan on glassing the inside of the hull, replace and glass the stringers, and replace the transom. After that's all done and the foam is in, I'll need to glass in the deck.
Thanks again,
Tom

 

[tpenfield]

I use VE resin, more than poly ('cuz that is what my boat is made from). Adhesion is supposed to be better than poly resin. From my experience, the set-up and cure times are much longer with VE and the fumes are like chemical warfare.

Cost is about 30-50% more than poly . . .

 

[pauloman]

there is a reason why 99% of boar repair is done with epoxy resin....

 

[tpenfield]

there is a reason why 99% of boat repair is done with epoxy resin....

99% . . . :noidea: is that a published statistic?

 

[Woodonglass]

there is a reason why 99% of boar repair is done with epoxy resin....

I know PM is a serious proponent for the use of Epoxy. He has serious credentials in the field. Therefore he is a bit prejeduced towards it's use. Just like I am towards Poly because of my years of experience with it. Each resin has it's place. I'm 99% sure PM's statistical evaluation is incorrect. This forum is a testament to that. For me the bottom line is if you do the prep right Poly works just fine. If you have the cash and don't mind waiting longer use epoxy.

 

[SweeperForce]

Well I think I have a plan of attack. Using VE for the transom and the stringer where strength is a must. Then switch to poly for the deck. I'm not opposed of using epoxy but I read the it should be used for the last layer, because nothing sticks to expoxy.
Thanks for all the advice and info.
Tom

 

[ondarvr]

there is a reason why 99% of boar repair is done with epoxy resin....

pauloman is a good guy and knowledgeable, but....

He frequently makes statements like this that are totally false, 99.999999% of repairs on old polyester boats are made with polyester resin, there is a very small segment of the industry that does epoxy repairs, and there are reasons to use it in some situations. He sells epoxy, so yes, 99% of the people he comes in contact with use epoxy..

As for which resin to use, it won't make a big difference, if any, in the final product, all of the resins will do the job and hold up well. The skill and attention to detail are far more important than the resin type when it comes to a successful repair.

 

[jbcurt00]

As for which resin to use, it won't make a big difference, if any, in the final product, all of the resins will do the job and hold up well. The skill and attention to detail are far more important than the resin type when it comes to a successful repair.

It came up elsewhere, and IIRC you and Mike (WOG) discussed it, but for those that aren't aware and weren't involved in that conversation, the oft repeated and generally accepted practice around the iboat's dry dock is that the:

'Gelcoat won't adhere properly to epoxy' advice is still valid, esp for DIY backyard boat builders that don't work regularly and long term with any of those products..

Correct?

 

[ondarvr]

'Gelcoat won't adhere properly to epoxy' advice is still valid, esp for DIY backyard boat builders that don't work regularly and long term with any of those products..

Correct?

Correct, it can be done, and we sell gel coats that are compatible with epoxy, but there are so many different epoxies and gel coats, that to say it "will" work with all of them could lead to some major failures. It's safer to say it won't work well, I'd rather error on that side when giving advise.

 

[Daniel1947]

Once again an interesting discussion. I would by no means ever doubt many of the experts here on the forum. Men like Ondarvr, Jbcurt00 and Woodonglass have probably forgotten more about fiberglass and resins then I will ever know. I offer the following you tube links only as some additional thought on the subject, not to find fault. As I believe probably the biggest problems in fiberglass construction and/or repair is improper preparation, I offer this info from the guy over at Boatworks.com. Like I stated, this is only to provide possible room for more discussion.

 

[Daniel1947]

This is part two of his video where he actually does somewhat of a test.

 

[jbcurt00]

Thats exactly why I asked the question Daniel. ^^^

Isnt long term, used compatible gelcoat and epoxy all from 1 supplier and done by an expert in a somewhat controlled environment.

For DIY purposes, Ondarvr's advice is still recommended.

 

[Woodonglass]

Yup ^^^ this is 1000% Korrectamundo!!! It's kinda like painting. You don't mix Oil based Paint with Water based paint and IMHO you shouldn't mix Epoxy resin with Polyester resin. Gelcoat is Polyester based sooooo it's gunna be naturally compatible with the Base coat of resin. The Video IS interesting in the fact that the MFG is able to in some shape or form obtain a mechanical bond between the two dissimilar products. For me, I prefer to stay in the same family of products. Just makes more sense. But like I say...I AM and OLD DUMB OKIE soooo, There is that to consider!!!

 

[Daniel1947]

Like I said...was only offered for further discussion. Personally, I will use Poly...see no reason not to use poly since it is just about compatible with everything. Except maybe Epoxy...:facepalm::lol:

 

[Woodonglass]

Yup, and a VERY Interesting Video. I learned some things from it. Especially for small patch work etc. I won't be afraid to tell people it's ok to do small patch work on a transom with epoxy and then apply gelcoat. Since the transom doesn't flex, based on the video, I'd say that if they used the West Systems epoxy and a good quality gelcoat they should have more than acceptable results. Never would have done that, If I hadn't seen the video. Thanks for Posting it.

 

[ondarvr]

That is the most impressive bond testing I've ever seen for gel coat to epoxy, most testing doesn't show results like that. The official testing is done differently, but I would trust the results done in this way. Since this testing show's adhesion far beyond what's typically found, I would still be a little shy of saying go for it without doing it myself with several different gel coats and epoxies. In my prior testing, unless the gel coat was formulated for use with epoxy the results weren't nearly as good.