Technical Painting a fiberglass car?

Discussing boats? No, but product cross-applications are fair game.
Marcus...

 

IMHO pretty much nailed it.

Key points with polyester are to make sure that the material is properly catylized. 1-3% NOT less, NOT more, is a good guideline but follow the manufacturers instructions.
Gel coats come in many formulations... A good "finish" gel coat will be hard to hold a polish and be more susceptible to cracking than a "sandable" gel coat which in turn is more flexible and will dull quickly.
Get all the old paint and primer off... they are bubbling now and will bubble later.
If you want to use epoxy do so, but over the polyester work, your top coat may want an epoxy primer.

A Kaiser Darin should also be HAMB friendly.

 

Any bad spots, marglass then filler, primer, paint.

 

DP-40 versus DP-90 is just the color of the primer. It's all been replaced with LF (lead free) version.

There are 2 catalysts that can be used in all colors. DP401 recommended for plastics, DP402 general. The 5 colors, codes, catalyst use are in the link below
https://buyat.ppg.com/refinishprodu...x?FileID=33355840-14d2-41d5-96ff-049c5537ad9f

 

i have built a couple 'glass parts. The tilt hood for my Willys and the Mysterion reproduction body. Both were gel coated in the mold then 'glas laid on that. Gel coat is intended to provide a uniform workable surface so tyou aren't forced to try to put a fine finish on cured polyester laminating resin and glass mat. It is like cured polyester primer and is very nice to work.

For your project I never like to strip solid existing paint. If still stuck to the body and not weathered, it is a much better starting point than a stripped, chemically exposed bare surface. The hard work has been done in achieving a bonded coating. As mentioned above, grind out all checked. weathered 'glass to solid surface. Repair to workable surface with your favorite poly filler. Then sand entire car with 220 and prime with catalyzed poly filler/primer. VERY important to use only catalyzed coatings. They don't shrink. Finish block sand that to a perfect surface for your final catalyzedurethane base coat/color coat finish.

I agree with Moriarity gel coat is a fantastic surface to work. In my experience though it is best as the entire surface on a part, a little problematic to use as a spot repair product. Poly primer is just as good as gel coat and much easier to use for that purpose.

Incidentally my Willys hood is 25+ years old and counting and aside from a few rock chips and a spider crack or two where I over stressed it over the years, it looks brand new.

 

no jell coat in 1959....
just going to use high build primer (liquid bondo) and seal it, then paint with 1960 corvette cascade green/white

 

WOW - if those are your builds MORIARITY - WOW - HA - but not sure about sitting under that plastic bubble on a HOT UMMER day - HA. NEATO build and color. I have had good results with plastic media blasting - BUT - as with anything involving 'high-pressure' - it is always best to proceed with CAUTION. As far a chemical stripping - the ONLY sort of paint stripper anyone should ever use on ANY surface is COOPERS from NEW ZEALAND - but as with any chemicals on a plastic/fibreglass body - again proceed with CAUTION - a 'hungry' plastic/fibre surface can 'hold the chemicals for you for a later date' - HA - and then present them to you again - just at the WRONG time. One memory of working on a plastic body car taught me --- DO NOT STAND in certain areas - HA - because when you hear a LOUD 'CRACKING' noise - you know two things - you just found a weak spot that you should NOT have stood on to gain access to another area - OR - you need to lose some weight - HA. CHEERS from AUSTRALIA.

 

I cruzed this thread and didn’t see any reference to this cars serial number or production date. The early Avanti production was plagued with paint bubbles and almost every car was repainted within the first handful of years. The cause was a nearly nonexistent jelcoat layer that was wet sanded thru at the factory. The fiberglass strands absorb the water… then cause bubbles shortly after the paint is applied. As I understand, the proper way to fix is to DRY strip the car and apply a liberal gel coat layer to seal in any moisture. I’m no painter, just another Avanti owner passing along the “word on the street”

 

Can you repair as needed and buff out the exiting paint? It's worth a try to develop you skills and limit the cost and scope of your project. I am assuming when you say the bulk of the paint is intact and has a few problem areas, it could be repaired. The age of the imron is irrelevant. I've revived a few in the past and it was more satisfying than a repaint.

 

I will second the use of razor blades on fiberglass. I did a fiberglass cobra body and it really was pretty simple and it came out well. Grab a pack of blades and holder and have at it. If you’re not up to it you only lost a little time and less than $10 in supplies.