Fiberglassing below 65 degrees

[olmpilot]

I'm finally in the process of putting things back together in my project and have begun the fiberglass parts of the project. Although I have read many posts about fiberglass, I haven't found one specific to my situation and have some questions. Right now, I'm just doing buildup and repair of low spots or glassing in/covering "underfloor" supports and cross members. <br /><br />1. Is there a structural disadvantage to fiberglassing at or under 65 degrees using West 105, other than the lengthened harden time? I've done a couple small spots and just let them cure overnight and they seem hard enough, and the can says it can be used down to 40 degrees, which is why I got it... I'm in WA after all!<br /><br />2. The guy at Boaters World told me to use "laminating resin" for the first layer application and then apply subsequent layers with the epoxy resin. Is this good practice?<br /><br />3. Is it okay to apply a layer, sand and clean the next day and then apply a 2nd layer if necessary to get the right height/thickness?<br /><br />I just want to get as much done as possible so that when the hot weather comes I can concentrate on the main flooring, which I was told it should be 70-80 degrees out in order to finish.<br /><br />Sorry if this is covered somewhere, but I've spent so much time at the computer searching, I would rather be working in the boat if I can. <br /><br />Thanks!

 

[Winger Ed.]

Re: Fiberglassing below 65 degrees

I'd use the epoxy resin throughout. Different materials often times don't like sticking to each other, and the epoxys are much stronger than the old style resins with the little tube of hardener.<br /><br />The temp. is OK. For most things, anything above 50 degrees F. is liveable.<br /><br />I do all my build ups in one application. Get it a little high, then block it off with a 36 grit sander or grinder. Its a mess, but much faster than playing around with multiple pours and layers. If you're going to have to finish the spot out smooth--- shape/grind it a bit low, then put a skim coat of a catalyzed spot putty on it and go from there.<br /><br />Like I said-- <br />its messy, but it cuts your time down to saving one day per layer that you'd otherwise have to lay up. Build up one day, grind the next and spot putty it, then start slicking it off for painting a few minutes later.<br /><br />And, in that application, I can't see how you'd give up any strength or add weight by not doing multiple layers. After all, the boat manufacturere do it everything in one setting when they build up a hull in the mold.

 

[ondarvr]

Re: Fiberglassing below 65 degrees

I have a couple of questions for you.<br /><br />#2 "use laminating resin" then epoxy. If you mean polyester laminating resin then epoxy, don't do it, its best not to mix and match.<br /><br />If you are using the same product, I'm not sure why 65 degrees or lower is OK for one repair, but then not OK when doing the floor. <br /><br />If you are you using polyester resin in some areas, like the floor and epoxy in others, then yes temperature is important. It is not recommended to use polyesters below 60*, people do it all the time though. The chemical reations that need to take place require heat to be completed correctly, below 60* it not always, but can be, incomplete. It just may not get as hard and strong as it should. If you have a thick laminate it will normally generate enough heat on its own even if it is cool out, but if it is thinner, it may not cure completly.<br /><br />If this is all epoxy, pay no attention to me, I can't speak for West Systems.

 

[olmpilot]

Re: Fiberglassing below 65 degrees

I just looked and yes, the laminating resin is poly. It's Evercoat Laminating Resin and was specifically given to me by the guy at BW along with a half gallon of the West 105 epoxy resin. I'm totally new to this so I didn't even think to ask if it was poly or epoxy.<br /><br />So instead of using the laminating resin to coat/seal the bottom of the main floor, I should just use the epoxy instead if it is going to be below 65?<br /><br />Also, I was told that the resin would cure better the hotter the weather was. However, I'm suspecting that doing a whole floor, I would have more working time if it was indeed cooler and would prefer to do it that way, if in "time" the cure would be the same if it was 65 rather than 80?<br /><br />I'm thinking I like the sound of this and may be able to be done BEFORE the end of June if I really don't need a hot summer day to finish the job! <br /><br />Thanks Guys!

 

[ondarvr]

Re: Fiberglassing below 65 degrees

Epoxy will bond better to most surfaces than poly will and is stronger, but for the most part, on repairs like this you won't be able to tell the difference between the two. It was built with poly and normally it's the wood that fails not the laminate. Poly bonds to poly very well, if it didn't most boats would fall apart, so its OK to use poly when doing repairs. Epoxy is much better than poly for other things though.