To Gel Coat or Not?

[Andy C.]

Hello; I'm in the process of restoring my 1963 coupe. The body is in RAW fiberglass. I would like some suggestions as to the pros and cons in applying a Gel Coat on the body, or epoxy primer or polyester primers or Standox primer or preparakote,etc. I would like a product/proceedure that will stand the test of time and not shrink over time. Any thoughts and ideas would be greatly appreciated. Thanks, Andy

[Dick W.]

Re: To Gel Coat or Not?

I think that you will find some here are very adamant about gel coating while others like to use PPG's DP product as a sealer on the glass, K-36 as a primer surfacer, and seal with DP immediately prior to painting. Personally I have had very good luck with the latter. I have seen 5 of the cars we painted 10 to 23 years ago and have not found any shrinkage or evidenance to body repairs showing thru. Some of the body's were in pretty rough shape.

[Stewart A.]

Re: To Gel Coat or Not?

I believe the gel coats are very hard to sand ! The newer stuff (Polyesters) are suppose to be easier to sand than gel coat. I have used Polyesters but not convinced that the shrinkage and expansion rates are what we need on Glass but I am happy with the outcome of Ployester.
I must look into the shrinkage and expansion on glass compared to steel panels. I personally think the corvette bodies expand and shrink a lot more than steel but I could be wrong. If they do expand and shrink more than steel I would want a shell that's as tough as hell. ( gel coat ).
Try not to use fillers if you can they shrink on glass pretty quick in the heat. I left my car for 3 months before I painted the hood and still got shrinkage on the fillers I used. My hood was really bad so I'm still happy with the result. I hardly used any filler and the filler I used has moved about under there. I must admit I did have the car out in the sun on a 120 degree day!! I noticed it after that ?
I would look into it really thorough before you make a decision. There are millions of panel shops that will give you there 10 cents worth but have never worked on fiber glass.
I don't have any shrinkage on the edges where the polyester would show up shrinkage. So it does work ! Stewy

[Bill C.]

Re: To Gel Coat or Not?

Gel Coat from Ecklers, talk to the tech line. You can thin it with acetone before spraying and it makes a world of a difference when it comes to sanding out the orange peel. Because there is not much.

Makes it a no brainer with no more "to hard to sand" excuses. I still let it sit for monthes if possible before doing any further work.

I have used the PPG NCP instead a couple of times where I wish I had used gelcoat, I can tell the difference.
If the car has had a lot of "work" to the body I would never consider anything but gelcoat.
If its all nice old fiberglass etc, I would use the NCP primer/surfacer as nothing under it is fresh and needs to be held down

[John D.]

Re: To Gel Coat or Not?

Andy, One of my Corvette friends didn't listen to me (and others). He did not Gel coat his car and it was put together like a kit car. Body had fender flares and other custom work done to it before he started.
He used a PPG product. I don't know which one as I am not into painting except for a spray can. Anyhow when the car was done and sat a while it looked like crapola.
Gel coat is your answer.
Now my 63, the LWC had zero body work done to it and still got gel coated an eon ago. The lacquer has held up extremely well. Car was painted in early 80's and only has a couple of cracks. Gel coat your Z06 Angelo. JD

[Timothy B.]

Re: To Gel Coat or Not?

Andy,

When I painted my 63 coupe in 1981 I had installed a new front, (all GM panels except side fenders) and new GM rear quarters. No gel coat but PPG DP40 green epoxy primer over glass then PPG sandable lacquer primer, once red then gray to use as leveling teletale, six weeks in between.

I painted the PPG white lacquer four coats let it sit in sun 6 weeks then four coats six weeks then wet sand and buff. The car still looks great except front fender seems show just a little bit. I can send pics if you would like to see.

I have never used gel coat but I suspect there are repairs where that may be better. Most any repair on a horizontal surface will show and over time some on the vertical.

[Tom A.]

Re: To Gel Coat or Not?

After years of trying every reasonble undercoat I have found gel-coat to be the only sure prevention for repair shrinkage. For all the work involved in body restoration is it really worth saving a little work or money on materials to take a chance on it all going south after a year or two? It's always cheapest to use the best method first. Disappointment and redos really suck.
I like the Ecklers product but follow directions carefully especially concerning mil thickness.