How do you fix hair line cracks

[Jcon]

A friend gave me a front spoiler I'm thinking about puuting on the SC. It fiberglass and has several small hairline cracks. What do I need to do before I paint it to get rid of the cracks?

Thanks

[RoninLB]

cracks in the paint?

[ben parrish]

You need to grind a "v" groove along the full length of the cracks. Make sure that you don't go too deep but through the gell coat. Once you get this done, sand the area around the crack to assure proper bonding. Fill the grooves with an appropiate filler that has the proper"flex" needed. Sand, prime, and paint. Not too hard but if you don't grind into the cracks they will come back.
Good luck.

[HawgRyder]

Another trick is to cut a slit across the crack (at 90deg to the crack) and press in a piece of hard material...like metal or hard wood.
Then when you reglass the area it will be reinforced.
Bob

[slater]

If you are looking for a quick and easy fix, there is a product called Captain Tolley's Creeping Crack Cure. It is a penetration epoxy that is so thin that it will seap into the hairline cracks in gell coat ans seal them up. You can find it at most marine stores, and I have had a lot of luck using it in tth past on other fiberglass things.

[Kemo]

Back in the early 90's i was into the personal watercraft racing scene. I had some VERY severe damage including ever present hairline cracks. The best fix I found is using a dremel to get out all the cracked fiberglass. Then I would drill small holes every inch or so just on each side of the crack line. Then I would "hourglass" the drilled holes with the dremel. Then I would buy the glass matting, the good stuff that comes in a roll. Using duct tape on the external side, I would tape up the area to be repaired and work mainly on the inside of the hull. Anyway, I would cut plenty of strips from the matting such that the strips are slightly wider than the crack that has been dremeled out, including the holes drilled. Cut plenty of matting. Then I would mix the resin according to specs and start brushing it in with a paint brush. Get a good layer of resin down and then place in the matting. press the matting in place with the brush and then apply some more resin. Do this about 5-8 times getting plenty of the matting in the cracks and holes. Once everything had set up, I would remove the tape and then sand the external area down pretty well, just making it a bit shallower out to just past the holes. Then i would repeat with 1-3 layers of matting on the external. Once everything had cured really well, I would just sand the external hull down to make it look good.

This might be a little overkill, but I never had one of the repairs come apart on me, which is surprising given the amount of pounding those machines took.

If you are gonna do the "Valley" procedure, I cant see how drilling a hole at the very end of the crack could hurt either. Good luck and be sure and post some pics of the project. Im sure you are not the only one with crack in the fiberglass.