Fiberglassing question

[Luciano Burtini]

Okay, this question will mark me as an obvious newbie, but so be it. I am getting close to finishing my cedar strip kayak and have been applying the fiberglass. I am using 6oz cloth and West Systems 105/207. The fiberglassing is going pretty good, but I am working outdoors in 30 degree weather. I have been trying to work in the evenings as the temperature is falling to prevent outgassing. The issue that I am encountering is that each time I put on a coat of epoxy, between the trapped bugs (lots of bugs) and just plain old rough spots, I am forced to sand. After I sand, the hull takes on the dull look of a sanded boat.

My question, when I am happy with the amount of epoxy, do I have to get one final coat on the boat with no subsequent sanding to bring back the shine, or will a final sand followed by application of spar varnish also restore the shine? I am starting to feel like I am chasing my tail...

[Frank Hagan]

By "30" you mean 30 C, right? I think that's above 80 F. That should certainly be warm enough.

One thing you might try is sanding down to where you're happy that all bugs are gone and then use a plastic body filler spreader, like they use for Bondo, and put on what I call a "skim coat". Using a small amount of epoxy, use the spreader to lay down a very thin coat. Very thin ... you are using the spreader like you would use a squeegee for the windows. This may help minimize bugs actually sticking in it while it cures, because there isn't "depth" to the coating to allow them to really get stuck.

Or try working earlier in the day if that's when you have less bugs. Generally warmer temps will kick the epoxy off sooner.

[John Bailey]

The spar varnish will bring the shine back. And do make sure you put a spar varnish on that has good sun inhibiting factors because sun is death on the epoxy without it.

John

[Luciano Burtini]

Thanks for the comments.

Yes, 30C+, actually the last few days it has been 90-100 degF. Too hot for me and not much fun with epoxy either. The bugs are unbelievable. As soon as I put epoxy on it is covered in tiny little bugs! Doesn't seem to matter if it is in the morning or the evening, I still catch them.

I plan on using spar varnish with UV protection for the last coat but was getting a little frustrated that I have to sand every epoxy coat. I may have to find a protected area to do the varnish.

Luciano

[Jon van der Linden]

I have some experience with surfboards, which may translate well for your kayak. Part of your problem with getting a nice surface may be inherent in your use of West Systems epoxy. I've used it and always had trouble with that aspect... and it's yellow. For surfboards I'm using epoxy from a company called Resin Research which is water clear and can be brought to a gloss finish very easily. (Just as an fyi this is not a poly resin like traditional surfboards use.)

Simple procedure: 1st coat is with the glass, 2nd coat to fill dimples in the weave (with light sanding to remove any noticeable bumps, don't hit the cloth if you can help it), 3rd coat is the gloss coat which is sanded from about 220-600, then polished with a polishing compound (I use 3m automotive compounds which are easily available). This should give a high gloss coat. I believe this procedure is fairly universal for expoxies in this type of thin layup. The 207 epoxy is formulated to be coated with a varnish, so it's not expected to give a gloss coat.

The higher temperatures you're experiencing will almost always result in a better finish, just need to watch how fast it goes off - with the 207 you only have one formulation which can make that a little tricky, which may explain some of the rough spots you mentioned. I'm also reminded of my West System experience - bugs do seem to like it more than other epoxies I've used.

Good luck with the varnish.

[Mac McQuinn]

You will have to sand at least the last coat of epoxy to gain adhesion for the varnish top coat and always allow the epoxy to cure thoroughly before top-coating. I always give it 2-4 weeks and have never had a problem due to the varnish reacting to the epoxy oddly. I would try to find a building i could use for varnishing, seal all openings and put a fan in the window to exhaust fumes and always wear a mask. If you can borrow a window A/C unit, that's even better as it will control temps & humidity, keep out bugs and go a long way in giving a you a stellar, quick drying, blush-free varnish job. Take your time, keep your cool w/ the A/C unit and turn on some Thelonious Monk to makes things go smoothly. :cool:

Mac