C2 Fiberglas Primer Recommendation?

[David H.]

I need a recommendation for a specific brand of fiberglas primer. I've scraped and sanded the tubs underneath the wiper arm grills of all loose & potentially loose paint and sanded smooth (although some spots still have old paint). I plan to use a polyester primer as recommended in the archives and paint with semi-gloss black, but the local paint body shop is not sure what to order and it's expensive so I sure want to get the right stuff first time. Thank you for your help!
BTW the car has been previously stripped and re-painted and I don't believe they primed the tubs, causing the "new" paint to flake down there.

[Chuck S.]

Re: C2 Fiberglas Primer Recommendation?

Polyester primer??!! Do you have the thread reference? There must have been a context the statement has been removed from that would help us understand why polyester based primer would be required.

Ordinarily there is no reason to use a polyesther based primer...gelcoat is probably the best know "polyester primer", but it still has to be primed again with another material. I suspect the referenced discussion was about sealing trapped oils or solvents to prevent the paint from blistering...typically this care doesn't have to be taken unless you have contamination or recent repairs.

All primers bond to the fiberglass mechanically, so it doesn't matter what chemical base you use. In fact, epoxy primers will give you the best mechanical bond, particularly when applied to a clean, properly prepared substrate. If properly top coated within about a week (I prefer no more than a day), no sanding or scuffing is required...the top coats will chemically bond to the epoxy primer, and that's the best bond you can get. Whatever brand of primer you use, be sure to use the same brand top coat material...check the manufacturer's product data sheets to insure that the top coat (black paint) is compatible for use over the epoxy primer.

[David H.]

Re: C2 Fiberglas Primer Recommendation?

So Chuck I can just go to Wal-Mart and buy an epoxy primer, say Krylon, and that should work fine for the purpose I'm using it?

[Chuck S.]

Re: C2 Fiberglas Primer Recommendation?

Ohhhh!...I thought you said the body shop didn't know what to buy!

Let me say it this way: UNLESS you want this black to "flake off" just like the factory paint did, I would say buy real automotive paint and skip the spray cans. But, if you are going to do this with spray cans, frankly, I would just skip the primer; it'll be just like factory. Be advised; where you have patches of old paint remaining, those remnants will be visible underneath the new paint unless you feather sand the edges of every patch or remove the remanants.

The factory never deliberately primed any black out areas...they just sprayed the black where they wanted coverage, and it didn't matter if it only had primer overspray like the plenum/wiper compartments. Don't be too hard on the General about the paint flaking...they weren't designing these cars to still be collectibles 40 years later.

If you want this plenum paint to last FOREVER, and only be slightly "overrestored" (only discernible to the most discriminating and critical judge's eye), then prime the CLEAN AND PROPERLY PREPPED plenum with PPG DP90LF, and top coat with virtually any of the PPG topcoats.

DCC single stage urethane is probably easiest to find, but expensive; I believe DMR acrylic enamel is still available...these finishes, including the epoxy primer are catalyzed and should not be sprayed without proper supplied air breathing equipment and a spray booth. Whatever you chose, always consider the remainder of the restoration painting, so you can use this stuff later...at these prices, you DON'T want to have a bunch of this stuff moldering on the shelf as a fire hazard.

The problem with the "forever" approach is that automotive paint has to be flattened to the appropriate gloss level using DX 685 universal flattener (ALWAYS check product data sheets for compatibility); just tell your body shop or, er...painter that you want an "eggshell" or "satin" gloss level.

[David H.]

Re: C2 Fiberglas Primer Recommendation?

Chuck, you've given me some much needed insight and some mulling over to do.
Thank you very mcuh!