Compatible resin for repair

[Stephane]

It's me again :confused: .

Now i am looking to fix the repair in my floor but i am not sure about the choice of resin are compatible with the one that we use Donzi Marine in 1988 for a Ragazza 23 ?

I have the choice between epoxy, vinylestere or polyestere ?

If somebody have an idea about that it will be appreciate

Thanks

Stephane :wink:

[MOP]

Send Lenny a note he is the MAN! I called 3,000 miles today to get some straight poop.

Phil

[Audiofn]

Depends on the size of the repair and your experience with the different products. Polyester is fine to use on most stock boats. Donzis as most are made with Polyester resin. Vinnylester resin is stronger then polyester and is a good compomise to the cost of epoxy and the lack of strength of the polyesters.

Epoxy has 2000PSI of holding power
Vinnylester has 700
Polyester has 200

You can ALWAYS put epoxy on anything. You can not put esters on epoxy. If you plan to use gell coat and you use epoxy for the repair then you need to wash the repair with water to get the anial (sp) off the surface. Then you SHOULD prime it with Durratech primer. This is due to Gell coats being a polyester based product.

I personally use Vinnylesters on MOST of my repairs. I find it easier to work with the epoxy and I know it is MUCH stronger then that the boat was originally made with so I know I am making a improvement. The epoxy soaks into the glass slowly so you have to work it a lot harder then the esters. When you work with Epoxy it is also important to remember that it cures by volume (plus the hardener). It is important to get it out of the cup as fast as possible because if left in the cup it will get hot and cure MUCH faster then if spread out on the boat. Another advantage of Vinnylester is that you DO NOT have to sand btwn coats. It leaves a tacky surface so as long as you coat with in 2 days then you do not have to sand. This can be a HUGE time saver. I find that I can do more in less time with the esters, so they are my choice unless maximum strength is needed.

Jon

[gcarter]

From what I've read and experienced, every thing Audiofn says is true.
However, I've been tempted to try pigmented epoxies by System Three,
http://www.systemthree.com/p_clear_coat.asp

Now this particular one is very thin (like water) and has multiple uses, but I've been wondering about spraying it in lieu of gelcoat or paint. If anyone has tried this I would like to know.

George

[Audiofn]

That would probably spray out a lot like Gel Coat don't ya think? If that is the case sanding it would be a Mother Fer.

Jon

[Audiofn]

Oh ya if anyone wants a GREAT place to get Gel coat supplies and info and glass supplies then call up the guys at MINI CRAFT, 800-282-8244. They IMO are the best in the bus. They have their own Gel coat reducer that if you spray it properlylays out and only needs a very quick wet sand.

Jon

[gcarter]

Jon, I've used these products for osmotic blister repair. The Clear Coat is used as a penetrating epoxy to seal old 'glass, before you start making the repairs. It has probably one fourth the viscosity of gel coat.
My intention on suggesting this process is to get around the problem of going from esters, to epoxy, to esters for repairs. If a person could finish off a repair or refinish with epoxy, there might be some advantages.

Just wondering;
George

[Lenny]

I would just use what is already there and not over-anaylize the job. Vinylester and Isothalic and Polyester are all very compatible. I have done very little work with epoxy so I can't comment on that. The Vinylesters were in their infancy back then, and as then and even today, they are much more expensive than Polyesters. Isothalics a bit more than Polyester. Vinylester has become much more friendly tho to work with in recent years. I would say with 99.9% certainty that they DID NOT use any in the process in making your boat. Today, quality manufacturers use Vinylester for the skin-out of the hull (in mold) and then they might continue the lay-up with Isothalic or Polyester. Great manufactures will lay up an entire boat in Vinylester.

Keep it simple IMO.

[Audiofn]

Lenny when I redid all the stringers, bulkheads, and just about everything else in my Formula 302 I used Vinnylesters. I used them to do the fact that I knew I would get a better secondary bond with it and it is still stronger for a min. of additional price. I find zero difference btwn working with the vinnylesters and polys that I use. I also LOVE the fact that I do not have to sand btwn coats but it does require a top coat.... The secondary bonding is the main concern for me thus the added insurance of the vinnylester resin. Yes they make these boats with polyester resin but they are laying it all up fairly wett and getting that chemical bond. We poor bastard repair saps are all relying on a mechanical one. I have read in a few places that the Vinnylesters soften for a moment the polyester and it creates a chemical bond but I have not been able to confirm that with any glass guys that I trust. At any rate in the sceam of my Formula were I used about 15 gallons of resin Polyester would have cost me about 150.00 Vinnylester cost me about 360.00 and Epoxy probably would have cost me 700 or so. Those numbers are fairly small patato's when you are doing the work yourself..... :D:D

Jon

[bigman]

I just repaired the bottom strakes and some checks in the gell coat on my 68,2+3. I've used poly before nothing else. The West system was recommended to me by Jamestown Supply.I bought a 5$ book on how to apply it. It seems to work real good and the smell is almost none existent. It worked for me about the same way. You add a filler to it to thicken it for fairing. It isn't cheep but I didn't have too much to do. If you let it stand for more than 24 hours you do have to sand between coats. good luck, bigman.

[Audiofn]

Bigman good point about the smell. If this is something you are going to be doing in the home garage then the West System is DEFINATLY the way to go. Vinnylester is the worst fallowed closely by polyester. Vinnylester you really need a mask to use in any quantitiy (over a pint or so).

Jon