Fiberglass voids
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Hello,
I have recently purchased a fiberglass body for a car I’m building.
There are a lot of voids in edges and corners that need to be ground and filled I am wondering what is the best way to do it.
I started using Bondo-hair as someone recommended to me and then another person said Bondo products will fail after so many years on metal but he wasn’t sure about the fiberglass filler on fiberglass. Do I need to mix it with resin? Polyester or epoxy? I’d prefer not to if I don’t have to.I’m also buying Evercoat xtreme filler, how do I know how deep I can use the regular filler? I assume I can’t just fill voids with it on it’s own.
Thanks,
BryanIf it were me id ‘V’ the cracks out with a dremel or grinder fill them with long strand fiberglass(it the stuff with the resin and cloth) grind down the highs until its flush, that will give you the strength. Than apply a finishing glaze/putty to make the surface straight and smooth. I wouldnt bother with the filler.
I was worried if I did fiberglass it would just make more voids, I’m no better at glassing in corners than the manufacturer is. Especially with trying to push it into cracks, for me it usually just pops back out leaving an air pocket.
I did glass the back of the panels to add strength though.What if the panel is laid flat and resin is just poured into cracks?
The cracks aren’t all the way through the glass it’s just air pockets.
I’m just trying to avoid using actual glass and resin to fill because the strands spring back to being straight and don’t stay the shape I want it to.I can’t stand how long it takes for the stuff to dry.
Thanks
If the areas need any real strength, use resin and matting to repair it (not the cloth). Nothing else will give you the strenght you need, and you will not want the cracks to come through later.
To prep the damage, V it out slightly, so the damage is opened up (increasing surface area for the repair to bond to). grind the surrounding area at least several inches (to just expose the fiberglass). Then use a DA with coarse paper (80 grit) to feather back the paint/gel coat. The idea is that you need to open up enough bare fiberglass for your resin to adhere to. The resin should NOT go overtop of the gelcoat.
Use the glass matting and tear it (don’t cut nice sharp edges) into pieces adequate for the size of your repair. Use a paint brush to apply the resin mix to the part, then place on a piece of matting. Wet that completely with resin and apply another piece of matting (making sure to overlap the edge of the previous piece(s). Build up many layers making sure to overlap different edges every time, more random than structured. The repair should be a little thicker than needed, with no dry areas (all fibers should have resin, right to the very ends). And no bubbles, When you are applying the resin with the paint brush try dabbing it on (rather than brushing) this will prevent and help remove air bubbles.
After it has cured, you can carefully knock it down with a grinder until it is about uniform with the exisiting panel. Apply some good quality (standard) body filler and block smooth. When you are ready to prime, feather out the existing finish (Just gel coat?) and apply a good epoxy primer over you repair and any exposed fiberglass right upto the gelcoat. Then apply a good quality 2k urethane over the repair as you would prime any body job.
If you have problems with backing (if the damage is though in some spots) just about anything can be placed there to hold the resin in place until it cures. Some good materials to have are duct tape, aluminum tape, wax paper, scrap pieces of sheet aluminum (that can be bent to your contour and held in place during the repair)…etc
If you follow some crucial steps and have the tools and materials necessary, fiberglass repair can be fairly easy. Oh, and as a note, SMC resin is more expensive than glass resin. However, it uses cream hardener (just like filler) and can dry very fast. It is easy to use and adheres great to fiberglass. You may want to try it (just note that you CANNOT repair SMC with glass resin). For curing, you can use heat with either resin (such as a heat lamp, heater, heat gun etc), just be careful that you are not applying too much heat as it can boil the resin causing bubbles or even cause a fire.
Good luck
Tallon, you cannot repair any voids or cracks using any filler methods you need to do a structural repair
well explained said Ben, the only thing I do different is slightly v the back too for a strip or two that I put on first then the backing to hold that and the top in place(If there is access and aslong as its not too big, last thing you want is fiberglass dripping and drooping all over the place) or do one, one day and the other the next (top and bottom repair) I find you you sandwich patch you should NEVER worry about a failed repair.
Mike K
Yeah I use the matt
I have polyester but I heard that it won’t stick to existing polyester resin as well as epoxy would. Is this true?I was also wondering about attaching flanges because I want to reattach separated panels to have real seams.
I am guessing SMC resin will be good enough for that as well but wasn’t sure but I will have to look in to that.Thank you guys for the knowledge I hope to learn more
So epoxy primer is part of the repair? I need that AND the 2k primer?
More surprises lolI ordered some smc resin to try, can’t wait to get it.
I’m not sure about epoxy resins, I’ve always stuck to polyester resin for matting. Make sure your flanges are ATLEAST 5-6 layers thick or more of matting for good reinforcing, the other repairs talked about were generally cosmetic but now your talking structural.
Polyester will stick to polyester perfectly fine… that is the standard for repairs.
Mike K
For the repairs- Like Ben Said. BUT First make matting into very small pieces, saturate the matting with resin, Then apply matting to the surface. To reduce dry times just play with the amount of hardener and/or warm your surface using a heatlight.
I was thinking more like glassing metal tabs as flanges
Well first time tcpglobal has ever let me down.
I ordered the smc resin and it didn’t come with cream hardener, is it the same as the stuff that comes with body filler or do I need to get a hold of the right stuff?Thanks!
[quote=”Tallon” post=24588]Well first time tcpglobal has ever let me down.
I ordered the smc resin and it didn’t come with cream hardener, is it the same as the stuff that comes with body filler or do I need to get a hold of the right stuff?Thanks![/quote]
Not a big deal. The cream hardener is the same. If you don’t have enough, any local body supply jobber should be able to sell you a tube for a couple bucks.
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