I started with a simple project and it has gotton more and more miserable due to incomplete information here and in a bunch of marine forums. All I wanted to do was to repair a few minor gel coat chips as shown in the picture. So I happily set off chipping off all the loose gel coat to find that there was actually a large void under the gel coat. This is not uncommon with Scamps and is due to improper building technique that allowed air to remain trapped under the fiberglass when it was applied to the mold.
Once I removed all the gel coat that would come off easily with a scraper, I then ground the entire area down with the flap sand paper attachment on my grinder for a nice surface to fill. When choosing filler I did a lot of research on this site and others. A lot of people here have had luck with glass filled Bondo filler. All the information on marine forums said "DO NOT USE BONDO" because of issues with water absorption. Therefore I used West System Epoxy based on a recommendation from some people here and boat people love that stuff. I mixed in the colloidal silica filler until it was a nice peanut butter consistency and filled the void. Three layers later of epoxy I had a perfect surface. Everything was going well (I thought)
I then sanded my last layer of epoxy, washed with acetone and painted on some Evercoat single step gel coat and walked away figuring I was done with that repair. I should point out that the container of Evercoat gel coat says in large letters "DO NOT USE OVER EPOXY." However, there is a white paper on the West System website saying "go right ahead and ignore Evercoat, it works fine." I listened to the advice from West System because I had already bought the gel coat. I came back the next night only to see that my gel coat had gone all drippy and had not cured in most of the repair. Using that same batch of Gel coat I had also touched up one or two other areas. Those areas were fantastic, with a little sanding they were done. Therefore I know it was not a mixing problem. What had happened??
Well my first guess that I had simply blotted on too much and it had prevented proper curing was NOT correct, because my second attempt did the same thing. More internet research led me to a new conclusion: amine blush. Apparently epoxy when it cures can emit a waxy residue that needs to be washed off with soap and water (NOT Acetone, acetone will not remove it), before epoxy can be finished. This is especially true if you are using it has cooler temperatures or if the temperature is dropping during the cure (the exact conditions in my semi-heated garage). My next attempt will be to heat gun the epoxy for a little (hopefully not getting it too hot) to make damn sure it is fully cured, then wash repeatedly with soap and water, then gel coat one last time. If that doesn't work I will start looking into painting
options, or maybe I will just grind out all the epoxy and start again, but that does not seem like a good idea and I may just end up with a bunch of new holes in the camper that I need to fix.
The reason I hadn't gone straight to paint
was because it seemed easier and cheaper to simply repair a few spots and blend it into the rest of the camper rather than painting
over the entire shebang. If anybody has any suggestions for a paint
that I can use in a few spots that will blend into the present gel coat that would be great.
Here a few conclusions on gel coat repair that I have come to so far the hard way. First thing, use a Polyester based filler like Bondo to do the repair. Your Scamp
is made using a polyester based resin with fiberglass, not epoxy. It is better to keep everything Polyester based, because paints, gelcoat etc. work well with this base. If you are worried about water absorption causing issues in the future (very unlikely, but you never know), use a marine polyester resin instead of the Bondo, but DO NOT use epoxy if you want to gel coat to match the rest of the camper. Even painting
over epoxy is not the best idea because even if you sand it with 80 grit sand paper to get good physical adhesion between the paint
and epoxy, it will never be as durable because epoxy hates forming new chemical bonds with anything once it has cured. Painting is probably your best choice once you have erred and used epoxy for the repair.