Guys,
What is Gel Coat?
I hear, at car shows, guys ask if car has been re-gel coated or just painted ? ? ? (speaking of 60s Corvettes)
Did 50s-60s Corvettes use this process?
Do C5s - C6s ? I know the new cars use "Composit Plastic", not "Fiber Glass" per sae...
I had a GREAT Plastics lab in high school (30 yrs ago), we'd spray colored Gel Coat into a mold, let it dry, lay down fiberglass mat, then brush on some resin - Viola, a "Fiber Glass" part.
(We had a motorcycle fender mold, the class made about 50 fenders.)
Would a new paint job, on an older - 60s Corvette be re-gel coated? Or just (sanded and) painted ?
THANKS, Art

 

Gel coat is just fiberglass resin, that has color mixed in. In boats, instead of painting the finished glass, they actually put a layer of colored gel in the mold first, then spray in more resin and glass strands.

I think early cars may have used a coating of the "gel coat" to insure a smooth finish, but not for color. Unless a finish has deteriorated through the paint and actually eaten some of the resin away, I see no reason you would want to apply more resin. If you sanded deep enough to hit the glass strands, you might also need more resin.

I think today's parts (the ones with glass, no the smc) use very small glass particles, and can integrate it into one process. However, I hate body work, and am NOT an expert.

 

I will take a crack at this, but there are plenty out there who know more about it than I. First, I doubt if the newer cars with the more flexible panels have gel coat on their surfaces as did the older Corvettes. I think the term gel coat applies to the older Corvettes from the 50-s and 60s. As to whether, on these older Corvettes, the gel coat was a special step as you described in your high school project or just a part of the overall process whereby they tried to make sure the fiberglass reinforcement did not extend up to the surface I cannot say. In working on many of the older cars, it is not unusual to encouner places where the fibers do appear at the surface. Whether this is a result of the stripping or if they were than way from the beginning is not all that clear to me. Ekler's makes a good spray gel coat; it is probably available from other sources too. I do know the Ekler product is good. I think the accepted practice when restoring an older car is to apply new gel coat in any situation where it has been necessary to make fiberglass repairs, grind out and repair stress cracks, or where the original fibers are at the surface. Whether this new product you spray on is exactly the same kind of material as at the top of the original part I cannot say. I do know that the Ekler product after it is set is hard and relatively impervious to solvents in the top coat. So it provides a major asset in helping to prevent interaction problems between repaired areas, etc. and the solvents in the top coats. I would think it safe to say that most any high quality restoration has at least some gel coat applied in certain areas. If a body is in rough enough condition, it may have received a 100% application of gel coat. IMO, the practice of applying spray gel coat when restoring an older Corvette body is not a do-all-end-all, but it is a very useful tool that can improve the quality of the final finish and the longevity of that finish. IMO. Hope I have not been too far off the mark. Others with more experience can correct or supplement as needed. Hope this helps.

 

From my motorcycle mechanic days, I remember Harley Davidson made a big deal about going to GelCoat for the fiberglass saddlebags, etc. You could see a difference, no doubt about it. You could definitely tell that any imperfections in the paint were related to orange peel, after they went to GelCoat.

I also googled it and came up with this,

"Gel Coat, a polyester coating that is applied to the mold surface and becomes an integral part of the finished product. Available in most popular colors. Use to make fiberglass reinforced plastic parts and for repairs to existing gel coated parts."

Like David said, it helps to ensure a smooth finish.

 

Gelcoat was never used on older production Corvettes, and it is also not used on the new SMC panels.

The slick surface you see on old stripped Corvette body panels is actually the polyester resin used to make the panel. The catalyzed resin was poured onto the female mold half suface by workers using coffee cans to dip out of a barrel. Fiberglass mat of random fibers was then placed in the mold, and the heated mold halves brought together and held closed by a hydraulic press while the resin cured.

For Corvettes, gelcoat is strictly an aftermarket product used to improve the fiberglass surface quality. It also prevent solvents trapped in the fiberglass from bleeding out after the car is painted. Fiberglass is quite porous and will soak up oils and solvents that will ruin a fresh repaint. The gelcoat used on the old Corvettes (up through mid-seventies) is essentially a sprayable polyester resin which is catalyzed to shorten cure time. If you don't work quickly and clean the spray gun immediately, it will ruin a spray gun.

There is no accepted answer for using gelcoat in restoration projects; some painters will not do a repaint without applying gelcoat, while others refuse to use it because it's VERY labor intensive.