[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.