prime and paint

[brian3127]

i have read on here that once you fix a hole with fiberglass that you should prime and paint it

what kind of primer and paint should i use

 

[gcboat]

Re: prime and paint

Loaded question. Need to know what 'type' of fiberglass you used, where was it patched, i.e. bilge, topside, bottom? All those questions will come into play as to recommending what type of product to use - that will last.

 

[brian3127]

Re: prime and paint

i will be fixing a a 2 foot X 3in section of the keel on the boat. Where the roller of the trailer damaged it. I bought the boat 2 weeks ago had it out this last weekend. I floated it off the trailer because the roller was split in 2 and i put a new one on it while the boat was in the water.
I probably be using the fiberglass patch kits they have at walmart unless i should use something else. This will be the first time i do this on a boat. Will that work or should i go and get the stuff at a boat shop
there is about $10 difference between the 2, cheaper at walmart

 

[gcboat]

Re: prime and paint

O.K. - first off you will be needing to use a polyester based resin. Most boats are made with that. An epoxy resin ( although a lot stronger ) will not effectively bond to the poly so keep that in consideration. If you have a complete tear in the body then it would be almost impossible to fix without a glass / poly mix. Make certain that you do the proper prep before applying any repair work. There are lots of on line manuals to help you - the public library is usually loaded with fiberglass repair info as well. It's really hard to talk you through this process this way. Send us your progress.

 

[drewpster]

Re: prime and paint

O.K. - first off you will be needing to use a polyester based resin. Most boats are made with that. An epoxy resin ( although a lot stronger ) will not effectively bond to the poly so keep that in consideration.

First time I have heard of that. It is my understanding that epoxy is favorable in repairs because of its ability to bond. ?

 

[Tail_Gunner]

Re: prime and paint

Pretty easy answer Interlux Prime-Kote will seal any new glassing, from there it's the paint of your choice.

 

[ondarvr]

Re: prime and paint

Is there a hole in the keel, or did it just scrape off some of the gel coat and glass? If there's a hole that water can get through into the hull, then you need to check it from the inside to see if the foam and or wood is wet or rotten and it's a good idea to add some glass to the inside also. If it's just a scrape or gouge then normally filling it with glass from the outside and then using gel coat as the final layer will work. You should be able to get all of the supplies at Wal-Mart.

 

[brian3127]

Re: prime and paint

water is getting in

 

[Chris1956]

Re: prime and paint

Brian, You need to make a proper repair first. Grind out the damaged glass on the exterior keel area, until you get to dry, solid fiberglass. The area to be fixed should be tapered to allow a good wide bonding surface. wipe the area with acetone. if you can get to the inside the repair will be better and stronger. If you have any wet foam, you really need to get that out and repair from the inside. if not, use some epoxy resin and fiberglass cloth to make the repair. Since the hole is tapered, cut some cloth to fit just the center of the repair area. Now cut some a bit larger on all sides, which will sit on top of the smaller piece. Now a slightly larger piece. The goal is to increase the cloth size to fill the tapered hole, with multple layers.

Now mix up some epoxy and saturate the area and stick on the first layer of cloth. Stick on as many as will stick without falling off and wait for it to harden. Sand lightly and repeat.

Once the repair si complete, sand and prime with some polyurethane paint.

 

[andy6374]

Re: prime and paint

Just to clear up a previous post...


Poly can be applied over poly and epoxy can be applied over poly, BUT you can't poly over epoxy.

Epoxy is sometimes the preferred choice for a repair because at that stage all you are getting is a mechanical bond (not a chemical) and the mechanical bond of epoxy is superior to poly. However, some vinylester resins are getting quite strong.

 

[Chris1956]

Re: prime and paint

Andy and others. Polyester resin may be applied over epoxy resin, provided that the epoxy is fully cured and has been sanded to get a good "tooth" for the poly to grab onto. In actuality, this prep step should be done when applying epoxy over epoxy or poly over poly.

 

[andy6374]

Re: prime and paint

Chris-
I thought it was a chemcial problem not a mechanical. The epoxy renders the MEKP useless, and in effect it doesn't allow the poly to cure. I've heard people say it works with West systems, but I've nver seen it just heard. But what I have seen is a surface that was epoxied, sanded with a 36 grit grinding disk, wiped clean, and then gelcoat (pigmented poly resin) applied...never cured. I haven't ever tried to apply poly resin & glass over epoxy but I 've heard the same results.

You've had luck with this before?

 

[gcboat]

Re: prime and paint

Most often in reference to the gel coat issue you will need to cover it with some kind / type of plastic sheeting. I think that the resins in the gel coat will not kick off unless sealed. As far as the bonding between epoxy and poly I do stand corrected. They do make a good bond but it is the prep work that makes the difference. Too many folks fail in that issue and you have nothing more than saran wrap - bad analogy but the best I can come up with. :redface:

 

[drewpster]

Re: prime and paint

One issue with applying anything over cured epoxy is Amine blush. During the curing process epoxy produces a waxy coating on its surface that must be removed prior to coating over it. Solvents will not remove it and sanding will drive it down into the surface making it more difficult to remove. Most manufacturers recommend a scotch bright pad and water to remove it. There are non-blushing epoxies on the market. Mas epoxy being one. the trick with these epoxies is mixing it thoroughly and at the correct ratio. Seems complicated but it is not. Epoxy will yield a superior repair in my view and is worth the extra step of a little scrubbing.

 

[brian3127]

Re: prime and paint

ok thanks guys or all the info a friend of mine has done this type of work before he said he would help me do it

 

[ondarvr]

Re: prime and paint

Sorry for the hijack, but back to the bonding issue.

This comes up frequently and the anwser is the same, Don't use poly over epoxy. I know there's information out there saying if you this, this and that, it will work. If you have every tested the bond and I have, and our lab has done it also, you will find that it does sort of stick, but not well, the bond will typically fail much sooner than a poly to poly bond will. What's strange is that people don't think poly bonds well to anything and that's why they recommend epoxy, some of these same people say it's OK to use poly over epoxy, yet poly to poly bonds are typically very good, it's the prep work that's poor, poly to epoxy bonds are typically poor.

 

[Chris1956]

Re: prime and paint

Andy, Pigmented poly resin requires additional hardener (for some reason) to cure. That may have been part of your issue.

I have mixed epoxy and poly products on several occasions, without incident. When I have a repair that requires extra strength, I will use epoxy for the structural components of the repair. For example, I have put poly putty over the cured epoxy/glass and mat to fill in some imperfections and give some (non-structural) shaping to the repair. Never had a problem.

 

[ondarvr]

Re: prime and paint

Like I said , it does sort of stick, but if it's stressed or is hit by something, chunks can and will just pop off.