Epoxy over fiberglass - lifting

M

mach 1

Hi, long time lurker, first time poster here. I've had a bit of a 'hiccup' on this boat that I'm working on and I'd like to get some opinions on what went wrong. So here's what I did;

I put a new floor & built new seats/storage compartments in the boat and fiberglassed over everything. It then sat for about 2 weeks then I shot 1 heavy coat of SPI epoxy over the raw glass. (2.0 tip). The epoxy sat for about a week, then I decided that I wanted to spray in some bedliner in the storage compartments. So being that I was just outside the recoat window (epoxy was about 8 or 9 days old), I lightly scuffed up the epoxy then sprayed some of Dominion Sure Seals "Gator Guard II". (It's not really what I wanted to use, but it was readily available - I definitely wouldn't use it again.)

At this point everything was good. I then moved the boat outside & threw a tarp over it because I had another project I needed to bring into the garage. The boat sat outside for about a month, and its been quite hot here lately, the inside of the boat must've been cooking, because when I took off the tarp I saw that the epoxy & bedliner had lifted off the fiberglass.

Does anyone have any insight as to how I screwed this up? My only guess is that the fiberglass wasn't fully cured, and when the heat got to it, it started to gas off but it couldn't breathe because of the bedliner. (All the other areas where I epoxied over the fiberglass are fine, its just the areas with the bedliner that failed.)

dsc01046c.jpg

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First picture shows the compartment shortly after it was sprayed (sorry, don't have any closer shots)
Second picture shows the area as it is today.

Can't seem to embed the pics, they're hosted on imageshack, here are the direct links;
http://imageshack.us/photo/my-images/836/dsc01046c.jpg/
http://imageshack.us/photo/my-images/707/dsc01191us.jpg/

Any insight would be greatly appreciated.
Thanks!


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dsc01191us.jpg
 
The one picture where there is a chip missing and looks to be a step may give the clue.

If you look it looks like the bed liner and epoxy have stretched out and then laid back down.

That means it gassed, now from what who knows???
Cleaner in fiberglass?
Uncured fiberglass??
Trapped solvents in first coat of epoxy??? MY SECOND BEST GUESS.
Tarp air tight???? MY FIRST GUESS.

Peel a place and within 5 seconds have your nose down there and see what the smell is, it should tell you if its cleaner, paint or neutral smell.
 
unsanded fiberglass...my guess would be bondo brand and their wax content...everything should come off easily with stripper, then sand and reshoot
 
Thanks for the replies.

Barry- I didn't use any cleaner on the fiberglass prior to epoxy. Yes, the tarp was pretty tight on there, there was only area about 2 sq/ft that was open due to the shape of the transom.

I did like you suggested and I could smell the fiberglass resin plain as day.

flynams & bondo- Yes, you are correct in that I didn't sand the fiberglass before epoxy. I didn't think it was necessary because I didn't over saturate the mat with resin so the surface had lots of tooth already. Also, the resin I use is laminating resin (unwaxed) so it should accept being recoated without sanding. Oh, and it's not bondo brand, I buy it at the fiberglass supply store in large quantities (5 gal pails).

Here's a close up picture I took today of the underside of the epoxy/bedliner combo that chipped off, wouldn't that be enough texture for the epoxy to adhere to? http://img525.imageshack.us/img525/9004/dsc01192hn.jpg
 
Sorry, all fiberglass must be sanded before putting anything over it, or this will happen....everytime....you really should sand between double laminations as in mold making even if it is fresh, everytime...It's a common misconception that textured (like the mat texture of fiberglass) will give tooth for next coats. However, that's not true, only sanding of most any surface will give you the required mechanical tooth for adhesion of most any product applied over most any surface
 
Might be a combination of "all of the above", sure sorry to see it happen. I would suggest, in addition to sanding the 'glass and leaving the tarp off as much as possible, that you purchase SPI bedliner for use over the epoxy. It's possible that the solvent blend in the Dominion Sure Seal product is a bit on the hot side for this application.
 
flynams;21515 said:
Sorry, all fiberglass must be sanded before putting anything over it, or this will happen....everytime....you really should sand between double laminations as in mold making even if it is fresh, everytime...It's a common misconception that textured (like the mat texture of fiberglass) will give tooth for next coats. However, that's not true, only sanding of most any surface will give you the required mechanical tooth for adhesion of most any product applied over most any surface
Click to expand...

You know, I just reread this and saw how cold my response was. Im sorry for your problems, and I hope you can get it fixed to your satisfaction...this is why I don't post much, and I think I should consider even posting less. Good luck with your problem....Dave
 
I'd rather see you post more, Dave, I for one appreciate the expertise you bring to the board.

It's true that posts that are considerate and diplomatic might be better received, but I didn't really see anything wrong with what you wrote. Besides, practice makes perfect, right?
 
I find the laminating resin great for when you need it to set up but still need more resin, the surface stays sticky and the next coat bonds. But I prefer to have the final surface cured and sanded before paint. I use a coat of PVA to seal it so it will cure to the surface, then wash off the PVA and sand it. No fiberglass expert here but I get good info from the supplier and it's worked out for me.
 
Thanks for the responses guys. flynams- Don't worry, no hard feelings. I appreciate everyones feedback on this issue & I value the opinions of everyone on this forum.

Yea, I definitely should've used the SPI liner, I figured I was saving time by just buying what was on the shelf and not having to wait for shipping. Turned out it's not gonna be saving me any time after all, lol. I won't make that mistake again.

Never used the PVA before but I'm gonna try it out the next fiberglass project, always open to new ideas & improve my techniques.

Honestly, I'm not that upset about this, I just wanted to figure out what went wrong so that I can prevent it from happening again. Next time I'll give the fiberglass some much needed time in the sun to gas off, then sand before epoxy. Lesson learned.

Thanks again.
 
mach 1;21554 said:
Thanks for the responses guys. flynams- Don't worry, no hard feelings. I appreciate everyones feedback on this issue & I value the opinions of everyone on this forum.

Yea, I definitely should've used the SPI liner, I figured I was saving time by just buying what was on the shelf and not having to wait for shipping. Turned out it's not gonna be saving me any time after all, lol. I won't make that mistake again.

Next time I'll give the fiberglass some much needed time in the sun to gas off, then sand before epoxy. Lesson learned.

Your fiberglass was plenty cured, you can expoxy the next day if need be...just need to sand
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