fiberglass, repairing and sanding/painting

DraykenK

DraykenK

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Canton, OH, United States
I purchased a front grill. (Ya, I know, most people hate them) Anyways, it is fiberglass. It has a small crack on one of the tabs. How difficult do you think it would be too fix? And how? It is in a spot that won't be seen, so it doesn't have to be perfect. Also, it needs sanded slightly in a few spots, before I paint. Just some fine sandpaper? Any recommendations on paint? Just looking to do matte black I think.
 
While I've never repaired fiberglass personally, I have looked into it before (at one point I was going to repair something) enough to know that repairing something small like this would be easy.

I'll wait for someone more knowledgable to chime in, but FYI, I found numerous videos on YouTube back when I was looking, and all of them guided you through the process very well.
 
Pretty easy to repair with either some short strand fiberglass reinforced filler, or just some fiberglass resin and fiberglass cloth. Grind out the crack with a die grinder or knife to allow resin or filler to penetrate the crack, fill it, sand it smooth and prime.
 
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I have done several fiber repairs on my Vette, boat, and coach. Pretty much like has been said. However I also shot a sealer over the repair before primer. It seemed to work a bit better. Don't get overly aggressive with you sandpaper grit when close to painting. You will end up chasing scratches.
Good luck.
 
Stinger said:
I have done several fiber repairs on my Vette, boat, and coach. Pretty much like has been said. However I also shot a sealer over the repair before primer. It seemed to work a bit better. Don't get overly aggressive with you sandpaper grit when close to painting. You will end up chasing scratches.
Good luck.
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corvette you say? :D what year???
 
DraykenK said:
I purchased a front grill. (Ya, I know, most people hate them) Anyways, it is fiberglass. It has a small crack on one of the tabs. How difficult do you think it would be too fix? And how? It is in a spot that won't be seen, so it doesn't have to be perfect. Also, it needs sanded slightly in a few spots, before I paint. Just some fine sandpaper? Any recommendations on paint? Just looking to do matte black I think.
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If the tab is structural, you will need to repair it with polyester resin and fiberglass cloth or mat. The key to a successful repair is to get the crack feathered back and cut almost all the way through so the new cloth/mat has some surface area to lay into.

Second thing, most folks lay into too much resin. You only want to saturate the cloth/mat and have no excess pooling or in puddles on the cloth but not so little that you get air bubbles. Lay up resin stays sticky so you can keep building layers over a period of several days or weeks on large projects without having to prep the surface each time. Finish resins have a wax in them so they can be sanded. You can sand the lay up but just know to use a coarse grit so it clogs less and don't over sand. You can rough sand it and then shoot a polyester high build primer to fill the coarse scratches.

Build your lay up higher than the original surface so you can sand it flush or slightly below and then finish to the flush layer with some polyester body filler like Bondo.

Signed- someone who is very sad he knows how to do this crap.
 
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What was it? Sure broke like fiberglass. Got fixed like fiberglass. Maybe my memory has slipped a bit in those 47 years since I fixed the rear fender well lips.:rolleyes:
 
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Stinger said:
What was it? Sure broke like fiberglass. Got fixed like fiberglass. Maybe my memory has slipped a bit in those 47 years since I fixed the rear fender well lips.:rolleyes:
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I don't think they added any metal until the mid 70's when they put steel floor pans in them for protection from the exhaust. So the 69 should have been all fiberglass.
 
Stinger said:
What was it? Sure broke like fiberglass. Got fixed like fiberglass. Maybe my memory has slipped a bit in those 47 years since I fixed the rear fender well lips.:rolleyes:
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When I worked at the body shop, we had a 69 in to repair some fender damage. There was some question as to what resin to use and the body shop supply sent out epoxy for us to use instead of polyester. The reason they gave is GM changed the formulation of the "fiberglass" used in the manufacture of the car.

Digging around a bit, it does appear that you are more correct than I am and they didn't fully switch over to SMC until later. The good news is you can repair fiberglass with epoxy, but you can't repair SMC with polyester. The easiest way to tell is by looking at the inside of a panel. If it is smooth like the outside, it is probably SMC. TJ hardtops are SMC.

http://www.bodyshopbusiness.com/set-on-vettes/
 
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