Painting Fiberglass and Gelcoat questions

[Guest Anonymous]

I really need some help here. I wrecked the car last december, running it into a ditch. It cracked my front d.side fender fairly bad. Everything was intact, so I just put a ton of fiberglass on the bottom and basically bondo'ed the top smooth. I got the car painted, and it looked as good as new, although about 3 weeks after I got it painted, little cracks where I repaired it appeared. At first they were little, then spread out to the whole region of where I fixed the fiberglass. It really looks bad, like a spiderweb of cracks.

 

Now, I was told this is because I didn't put a getcoat over the area I fixed, and then I even talked to another guy who told me that even putting a gelcoat on wouldn't help it, and that when you crack fiberglass you can't really fix it, just get a whole new part(which isn't an option, frontend runs around 2grand). I was thinkin about getting it repainted, and was wondering what steps I could take so it wouldnt happen again. Thanks guys and i really want to get this fixed before the big import expo. Thanks again

 

Scott

[Guest Locutus]

I am no fiberglass expert, but I think when the crack is severe you need to drill a hole at the end before you repair it to keep it from spreading. You might also need some kind of bracing behind the repair to keep it from flexing to much.

[Guest Anonymous]

I agree, glass to glass repair after drilling the crack to stop it. Grind a bit of a bevel and lay on mat until its fairly level. Light grinding and sanding/bondo'ing and your done (or "And Bob's your uncle" to the Brits... ). Also look at where the material is cracking.. Does it need additional bracing to keep it from cracking?

 

Good Luck with it,

 

Lone

[Guest Anonymous]

What you need to do is grind the cracks way back bevel it and use fiber glass resin and fiber glass mat. Lay a coat of resin down and then lay your mat in it and brush more resin over it . Make sure that you soak it up with resin put up to three layers over it. Small pieces wok the best.

[Guest Anonymous]

Arlinvg has a good start to your repair,after you finish the glasswork use lightweight body filler to smooth the surface. You only need to drill cracks if they are single cracks. If your glass has a spiderweb look to it drilling isn't necessary, the problem is in the surface.I also highly recommend that you have a coat of gelcoat shot over the repaired area as it will help to prevent the spiderweb effect. I have found that the best place to get answers on Glass work is at a reputable boat repair shop.

[Guest Anonymous]

I have to agree and disagree with some of the replys.

 

First, fiberglass can be repaired. Using a good boat repair shop is a good idea. Fiberglass boats are repaired all the time.

 

Any fiberglass repair should be done using epoxy resin, NOT fiberglass resin. The reason is that regular polyester fiberglass resin has a shrinkage of 7-9%. This causes stress where the new fiberglass patch meets the existing fiberglass. Epoxy resin has less than 1% shrinkage. It should be noted that true Marine resin is epoxy, not polyester. Also, epoxy resin is what is recommended for exotic materials like carbon fiber.

 

Furthermore, there should not be a need to use much, if any, body filler if the patch is layed up and sanded correctly. Most body fillers will shrink which may cause the cracking mentioned. Not using the correct ratio of resin to cloth will cause the part to become brittle and crack. Another possible cause of cracking is insufficient cure time of the fiberglass/body filler before paint.

 

There are many good books on composite repair which may save much time and frustration in the long run. Worth going to a good bookstore and reading a couple over a cup of coffee even if you don't buy them.

Hope this helps.

 

[ September 11, 2001: Message edited by: KicknZ ]