Gelcoat repair

S

summerwind

Member
Joined
Jan 22, 2006
RO Number
20017
Messages
96
I have to patch a hole in the fiberglass. 1/2" x 1/2". Just a couple quick questions. What does the temp outside have to be for it to set properly, and what type of process, sanding, buffing etc after Gelcoat has been applied?
 
figure the time/temp. to set and cure similar to oil based paint. 70 degrees at least for several hours, although the gelcoat will cure in less time. Have the gelcoat and catalyst at 75 degrees or more before starting.
Some recommend (after sanding the area) building the gelcoat up slightly higher than the surrounding area because you'll be sanding it back down. The patch will shrink slightly after curing.
Use a small sanding block.
After it's sanded down to level with the surrounding area, with such a small patch, you can buff it back by hand. Try 220 wet and dry if you've got a rough patch, then go lighter, like 300/400, then 600/800. When it's level, sand lightly with 1000 grit and finish with a polishing compound like Meguiar's HD Oxidation Remover (or 3m's), then a buff with a cleaner/wax. Use a terry cloth rag or similar.
Done right, you shouldn't be able to see much difference with the surrounding area. Hope your gelcoat color is a close match!

Buzz
Buzz
 
I believe sometimes taping plastic film tightly over the patch will allow the gelcoat to kick sufficiently to fully cure.
 
Gel coat has to covered with plastic film or wax paper to allow it to cure completely. You can also spray some PVA on it as well. Gel coat cures in the absence of air. If you don't do this, it will remain tacky. Oh, the other alternative is to add a wax additive to the gel coat. The wax forms a film over the gel coat as it cures, sealing out the air. You didn't mention the boat you have, but Spectrum Color makes gel coat repair kits for many boats and it has all the additives in it and matches the color pretty good.
 
Thanks, 2009 Sea Ray, white, I'll find out what type of white. The 1/2" x 1/2" spot, is basically a hole. Location is on the inside of the boat. there is an actual hole with the fiberglass gone. Is there anything in addition I would need to do so gelcoat doesn't fall thru? Should I also tape the area so the gelcoat doesn't adhere to adjacent areas that are just fine.
 
Sounds like a "void". I'd fill the hole with something like Marintex and then a layer of gelcoat. Can you get behind the hole?
 
If its an actual hole, it should be filled first. If its not a structural problem, I would use some polyester resin thickened with milled fibers. Marintex is great stuff, but its an epoxy material and the gel coat, which is polyester based, won't bond well to epoxy. If you can get to the back side of this hole, tape some wax paper over the back side, fill with the thickened polyester, leaving it a bit below the surface to allow for the gel coat. Sand the filled area with 80 grit, clean with acetone, then fill with gelcoat. allow the gel coat to cure for a few hours and then cover it with wax paper, plastic or spray with PVA (If you're using the spectrum stuff, no need for this as it has wax in it. Let it cure overnight, sand with 300, 400, 600, 800, buff with 3m super duty compound, then wax. If you post a pic of the damage, that would be helpful.
 
I can't get at the back side. Good idea I will take a pic and post. Thanks.
 
You must log in or register to reply here.
Back
Top