repairing targa top, in way over my head Options

[mightyohm]

Hi guys - I need some help with fiberglass repair. I have never worked on fiberglass before and I am in way over my head.

I am trying to refinish my Targa top. My top was already smoothed and painted when I bought the car, but the paint was flaking so I decided to refinish it.

I stripped the paint using fiberglass-safe stripper and got down to the gelcoat. That was pretty easy. Then I went over the top with a random orbit sander (100 grit) and got rid of the rest of the paint and got it cleaned up pretty well.

The problem is, the gelcoat has already been sanded through in many places, some of the damage must have been done by the PO and some by me making it worse. There is also a 1/8" divot in the top where the gelcoat is completely gone and it is into the fabric.

I want to prep the top for paint. I am having a professional body shop shoot the top, but I want to prep it as much as possible myself. I want to fill in the divot and low spots and also get the surface smooth. I think the PO used bondo.

Someone told me to use epoxy and a little bit of fiberglass cloth to fill in the divot. Does that sound ok? I have epoxy I bought from TAP plastics but I am not totally sure I know how to use it correctly.

I also think I have to "seal" the exposed fiberglass where the gelcoat has been sanded through. Is that correct? What can I use to seal it? I think if I just use bondo or have the shop prime it then the primer will leech into the fiberglass and cause pinholes.

Help please, I officially have no idea what I am doing. (IMG:style_emoticons/default/sad.gif)

Here are a couple pics:

[SpecialK]

Kevin,

Sounds like you have done this before! What kind of resin would you use? I have a 2 part epoxy, resin+hardener. I forget the cure time, maybe 15 minutes? It's from TAP plastics. Can epoxy be thinned with solvent, or do I have to use a polyester based resin? I like the idea of brushing it on over the whole top to get a smooth surface.

If you're using an epoxy resin use only MEK for thinning (forget about the paint thinner thing I said, it's good for cleaning, but my adversely effect the cure). And then just enough to make it thin enough to apply by brush. There's a mil. spec. for the exact ratio, but I can't recall it off hand (I always "eyeballed" it and never had a problem, use an eye dropper if you have one, cause it doesn't take much at all). You're looking for a shellac like consistency. Do a test on some scrap material to ensure a full cure. Also keep in mind that thinning the resin will increase its cure time, so don't panic if it takes longer than the flock repair mixture to completely harden, or tack in the case of the brush coats. We use Hysol EA956 epoxy resin for composite repairs at work (Boeing), but I don't recall seeing it anywhere outside of there.

If you determine with your test piece that the MEK isn't allowing a full cure (which can be tested by light sanding, if resin "balls up" rather than scuffing when sanded there's too much MEK in the mix, or the TAP resin isn't compatible with MEK). Then there's always plan 'B'.

Plan 'B': Your 15 min. cure (or is that the pot life?) is a little quick for covering such a large area as a Targa top. You definitely don't want it to gel before you can get the entire coat down, so you may consider purchasing a small kit (pint) of epoxy with a pot life of 1 hour or better for this method. Essentially, instead of using MEK to thin the epoxy enough for brushing, you'll use heat.

Mix your epoxy as per directions (adding hardener for a fast cure, or more resin to slow the cure is a big NO-NO), pour the contents of the cup onto the roof, and using a hair dryer, or heat gun on low, heat the resin while you spread it with your brush. Heating the resin thins it nicely, but also decreases the amount of time you have to work with it. Hence, 1 hr or better epoxy for this method.


Kevin