Fiberglass refinishing

[Dangerous Doug]

Well, while my Cobra is down with MSD Issues I figured I'd refinish the underside of my hood. I'm removing all of the blistered paint from the underside and what I find is a surface with exposed glass fibers. The paint blistering has been an issue from very early on. Same paint blistering issue in the trunk, as well.

I assume I need to seal the glass fiber surface with fiberglass epoxy, and then once it's fully cured sand it smooth. Do I use Bondo to smooth out the surface for painting, or smooth out the epoxy?

My plan is to use some ultra high-temp primer/paint to finish the surface.

I'm not a complete novice. I can use a rattle can and make small jobs look professional (It's almost all in sanding, sanding, sanding, and the rest is in the paint strokes).

Any advise for a fiberglass novice?

DD

[ERA Chas]

A. Brush gel-coat or resin on raw glass.
B. Make a template of the opening out of thin cardboard.Align the scoop opening with the rivet holes.
C. Cut sheet of .060" thick aluminum slightly larger than the opening. Roll a gentle contour into the sheet.
D. Get neoprene C-section tubing, cover the scoop opening edges.
E. Through-rivet scoop and aluminum.
F. Forget fiberglass mess forever.
Optional: anodize black like this:

[vector1]

I am not sure what the finish was on the underside of my hood that I got from JBL, but I had a painter spray it, he used a two part epoxy paint in hot rod black, prior to the paint he did a quick sand on it. Came out smooth and easy to handle although the glass texture was still there, no blistering.

[DAVID GAGNARD]

Originally Posted by Dangerous Doug

Well, while my Cobra is down with MSD Issues I figured I'd refinish the underside of my hood. I'm removing all of the blistered paint from the underside and what I find is a surface with exposed glass fibers. The paint blistering has been an issue from very early on. Same paint blistering issue in the trunk, as well.

I assume I need to seal the glass fiber surface with fiberglass epoxy, and then once it's fully cured sand it smooth. Do I use Bondo to smooth out the surface for painting, or smooth out the epoxy?

My plan is to use some ultra high-temp primer/paint to finish the surface.

I'm not a complete novice. I can use a rattle can and make small jobs look professional (It's almost all in sanding, sanding, sanding, and the rest is in the paint strokes).

Any advise for a fiberglass novice?

DD

Without seeing it,it's hard to tell,but if you have exposed fiberglass "hairs" sticking thru,I'd sand them down as best you can with a round dual action (DA sander) sander starting with say 80 grit.....if you can get it down pretty smooth,then I'd go with some fiberglass epoxy to smooth it up, you can get it pretty smooth when applying with a plastic bondo spreader, then sand smooth once cured with the DA sander and paint....I would NOT use bondo under the hood because of the heat....
sanding/working with fiberglass is a dirty job,where some kind of mask and put a good fan on right behind you to help blow away the fiberglass dust.....

David

[Bernica]

This worked out pretty good. Not sure you can get this paint anymore though....

[Bernica]

Originally Posted by Bernica

This worked out pretty good. Not sure you can get this paint anymore though....

Sorry, Won't let me re-post the pic since it's in an old post..I'll try to figure it out.....

[Bernica]

The pic is in my gallery.....

[DanEC]

What blistered the underside of both your hood and trunk both??? That is not normal - even from engine compartment heat - and the trunk????

If the blisters are bubbles in the paint from poor surface preparation and application then the only answer is to strip that back down to bare fiberglass again and re-prep the area before priming and painting.

ERA hoods and trunk panels are hand laid and the underside does exhibit fiberglass mat and fibers. If you want to smooth that to a finish comparable to the top surfaces it's a lot of work but very do-able. First - clean it with a good solvent like Dupont Prep Sol. I would do this 2 or 3 times before starting any heavy sanding or filler work. I sanded the bare fiberglass on mine down with 80 grit sandpaper - using plastic bondo spreaders and wrapping sandpaper around the edge to get back a ways under the perimeter frame lip. Use a thicker flexible rubber sanding pad as you don't want to sand with bare hands which will create finger grooves in the surface. Always sand in a criss-cross pattern to get a uniform surface.

Then I used Rage Gold filler and applied a uniform coat of filler over the entire surface. I sanded that down with 80 and then 120 paper and then repeated the process again down to about 180 paper. Then I shot several coats of SlickSand primer over the surface and began finish sanding that smooth down to 320 grit paper always using a thick rubber sanding pad for all sanding. The hood is not too bad but due to the tight curvature the trunk is kind of a pain to work on.

If you are preserving the paint on the outerside you will have to be extra careful because you will be working on these pieces while they are resting on their painted surfaces. Protecting existing paint will add to the difficulty of this job considerably. Body shop folding stands with rubber padding are the usual work place for this activity. I used the sandpaper on plastic spreaders to get under the outer frame lip again. Usually even after all of this you will still find a few pits, low areas, and small rough areas so touch up with Rage Gold again and then a last couple coats of SlickSand and more sanding down to 600. If using BC/CC you may want to sand to 800. After that a coat of sealer, finish paint, cut and buffing and you are done.

If I had the english wheels and metal working skills to make the aluminum panels ERAChas is referring to - or knew someone locally who did - I think I might take that route.

Good luck.

[ERA Chas]

Originally Posted by DanEC

If I had the english wheels and metal working skills to make the aluminum panels ERA Chas is referring to - or knew someone locally who did - I think I might take that route.

You don't have to be a panel-beater to do it. I just bought the material and did it myself. Just takes patience. The hood curve is very gentle in one direction only and is very easy to match. The riveting is what takes the most skill.

[Rick Parker]

ERA CHAS:
Was there any rattling at the outer edges or did you apply an adhesive or expanding filler??

[Dangerous Doug]

I don't want any rivets on my hood, so the aluminum panel method is out. I was considering having a custom fitted heat barrier made, but the problem becomes one of a heat-insensitive glue to hold it in place. I tried this with the heat barrier material before with not much luck.

The blistering isn't due to heat. It is occurring in the trunk as well, where heat isn't an issue.

The blistering started and was looking pretty bad. I put some heat-barrier material (glued) to try to cover it up and eventually it started to come loose. When I pulled this out, the remaining glue looked really $#itty. I was embarrassed to open my hood.

So far, I've scrapped all the glue off and sanded most of the original paint (I think it's trunk liner, or something, with a coat of black paint over it). Even if I just sand it down to fiberglass and throw a quick coat of paint on it this would look better than the blisters and glue slop.

I guess I need to think about how much work I want to put into this.
DD

[ERA Chas]

Originally Posted by Rick Parker

ERA CHAS:
Was there any rattling at the outer edges or did you apply an adhesive or expanding filler??

No Rick. No adhesives or fillers.
The curvature holds it nicely in tension. When riveted, it goes nowhere. No movement at all. Just use c-channel tubing on the scoop opening for a neat appearance.
I did this in 1991-picture taken in 2009. Looks the same today and cleans with Windex on a paper towel.