Hey guys. Tell me if you think I messed up. I am molding a rear spoiler off a late 90s camaro onto my 88 Fiero GT. I hate to say I didn't know so I'll say I didn't realize I was supposed to use a resin compatable with SMC. I used standard non-waxed 77 from Fibreglast.com. Do ya'll think it will be alright? The back of the car was in primer. Du Pont ERO primer to be exact. When I sanded the car to add the spoiler I used 60-80 grit paper and didn't sand down to the white smc. Will this make a diffrence? Thanks guys

Vinny

Well, it's like this. The Fieros are made up of at least 4 different exterior plastics. If I remember right, that large rear deck is SMC.
Here's a quote directly from Fibre Glast's web site...


A new composite material is gaining widespread use in the automotive, industrial, and personal watercraft markets that presents unique repair problems. It is called SMC, or Sheet Molded Compound. Recognizing SMC from other types of FRP composites
is critical so the proper repair can be performed. Parts made with SMC are produced in compression molds, so they are smooth on both the inside and outside. That is the first clue to look for when identifying them. Next, SMC parts do not have an outer gel coat, but they are usually painted or color molded. When the paint is sanded off, the underlying surface has a marble appearance. Finally, when damaged SMC is sanded, short coarse fibers are exposed and a dryer powdery dust is produced compared to conventional materials. These hints will make SMC identification quite straightforward. SMC is a polyester-based material, but it cannot be repaired with polyester resin. This is due to the mold release agent that is present throughout the entire SMC part. Unlike conventionally molded parts where release agents are applied to the mold surface, SMC is compounded with them in the resin mix for quicker processing. This means that as the damage is sanded to prepare a good bonding surface, fresh mold release agent is exposed. Polyester resin products are not strong enough to adhere to this surface. SMC SHOULD ONLY BE REPAIRED USING EPOXY-BASED RESINS, FILLERS AND ADHESIVES. When painting, use only catalyzed type paint systems.

I guess my first question is, if you didn't bond into the SMC what did you bond into??? Since there's no gel coat are you only resined into the old paint right now? Doesn't really matter because it sounds like you'll need to be re-doing this no matter what.

It is bonded to rough sanded new Du Pont ero primer

Ok. I realize now I have made a mistake. I think it won't be so hard to fix though. I'm not finised with the rear spoiler yet. I can grind out the fiberglass and get some of the evercoat smc compatable resin to redo it.

Next big question. Can I use a urathane primer on the whole car? I was going to buy Duponts ERO 3 part primer. For some reason I was told its one of the best primers you can get.

vinny

Vinny, yeah, doesn't sound to bad to fix. I don't use Dupont stuff so I can't comment on their products tech. I can tell you that it common for guys doing most of the Fiero plastic to use urethane primer on the whole car. You've got RIM, RRIM, SMC, and those soft bumper covers. All that stuff flex.s differently and some of it is prone to "the wave." I think urethane primer would be a good flexible surfacer for all of that. You might want to private message Old Dupont Guy and see if he knows anything special about that particualr Dupont product.

Vinny, this was an interesting paint thread over at a kit car forum that has helped me in the past. Several Fieros shown. It's worth a read...
http://www.kitcarsforum.com/technical-d ... for-cheap/