Question about factory primer (JohnZ?)
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Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
Question about factory primer (JohnZ?)
Just finished stripping the last of the factory original primer off my car ('68). I was curious as to why the stripper I used was able to soften the original paint and the primers used before the one repaint, but left the original red oxide primer completely untouched. Was this a different formulation from the original lacquer paint formulas that were used back then?
I've heard two different opinions: 1) that it is OK to leave the original primer in place to paint over when repainting, and 2) that the glass should be stripped absolutely bare. I decided to use 80 grit discs in my DA to strip the remaining red oxide primer down to bare glass thinking this is erring on the safe side. I will build up with the same paint family from here.
Thanks for any info that you might have.
I've heard two different opinions: 1) that it is OK to leave the original primer in place to paint over when repainting, and 2) that the glass should be stripped absolutely bare. I decided to use 80 grit discs in my DA to strip the remaining red oxide primer down to bare glass thinking this is erring on the safe side. I will build up with the same paint family from here.
Thanks for any info that you might have.
Team Owner
Joined: Oct 2000
Posts: 38,897
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From: Washington Michigan
The OEM red oxide lacquer primer was REALLY tough stuff, and was formulated as a kind of sealer as well, even though a gray sanding primer and separate sealer was applied over it before color. Be VERY careful with 80-grit removing it - you don't want to damage the "skin" surface of the fiberglass and expose any strands. 
Thread Starter
Melting Slicks
Joined: May 2001
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From: May help you? You can sure as hell try!
I was afraid that even though the red oxide primer wasn't removed by the stripper that it may have absorbed some of the chemicals to bleed back through later. Since I've already made some stress crack repairs that required stripping the primer completely in some areas I just went ahead and did all of it. I bought a gallon + quart of Eckler's spray gelcoat to seal the fiberglass strands if any. Any thought on the effectiveness of the spray gelcoat vs just using the epoxy sealers and 2-part primer/surfacers that are available? Again, I've heard opinions that gelcoat should be applied to bare glass and others who say it isn't necessary.
Thanks again John! As usual, your advice is always helpful.
Thanks again John! As usual, your advice is always helpful.
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
I was afraid that even though the red oxide primer wasn't removed by the stripper that it may have absorbed some of the chemicals to bleed back through later. Since I've already made some stress crack repairs that required stripping the primer completely in some areas I just went ahead and did all of it. I bought a gallon + quart of Eckler's spray gelcoat to seal the fiberglass strands if any. Any thought on the effectiveness of the spray gelcoat vs just using the epoxy sealers and 2-part primer/surfacers that are available? Again, I've heard opinions that gelcoat should be applied to bare glass and others who say it isn't necessary.
Thanks again John! As usual, your advice is always helpful.
Thanks again John! As usual, your advice is always helpful.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Corvettes never used gelcoat, but hand-laid boat hulls do; the body was primed over the natural fiberglass surface as the panels came out of the mold. I'm not a painter, but the painter who has done all of my cars for the last ten years uses PPG products exclusively, and uses their epoxy primers, sealers and surfacers; doesn't use any "gelcoat" or polyester-based surfacers under Deltron basecoat and Concept 2001 clearcoat. Sanding gelcoat is like sanding concrete.
Melting Slicks
Joined: Aug 2004
Posts: 3,078
Likes: 101
From: Riverhead New York
Years ago I painted many corvettes. Stress cracks are a difficult fix. I had great success with Crazy Glue. It is so thin it flows deep into the crack and is extremely strong. I never had a compatability problem when preparing the body for surfacing when I used this method. 
Melting Slicks
Joined: Sep 2003
Posts: 2,114
Likes: 33
From: ct
I only use a polyester based primer on bodys that have had alot of work done on them or the glass is in bad shape. Some cars have been stripped and repaired so many times that the body is a mess. The polyester primers are great for there high build and they dry sand very well. Gelcoat is not primer and is very hard to work with. If the body is not all beat up then use PPG DP epoxy primer for your base,do not sand DP. It comes in a few colors but is all the same stuff. then go over that with PPG K38. I like to tint each coat lighter and darker so as you are blocking you can see what you are doing. I sand the bare body with 80 grit. Then DP and K38. then I block that in with 180 grit. Then K38 again and finish with 320 dry then 500 wet. Been doing it this way for years and works fine. I just finished a customers 67 vert. on Fri. and I just finished sanding my 66 coupe this past week end. I hope to get my 66 in the booth this weekend. Ps what ever primer and undercoats you use, read and follow all the directions for safty and the job comming out right
Thread Starter
Melting Slicks
Joined: May 2001
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Likes: 4
From: May help you? You can sure as hell try!
I gave the spray gelcoat a try on my aftermarket L88 hood that I am painting before applying it the rest of the car. Good thing, too! The gelcoat application was a debacle. It sprayed on like ceiling texturing. Maybe it could have used a bit of thinning with acetone or maybe it wasn't cut out for spraying through an HVLP gun (I had the largest needle and orifice in it, meant for primers) but, whatever the cause, I could see it wasn't working out so wiped it all off with acetone before the junk started to cure.
On the recommendation of the guy at the local paint shop, I've since sprayed the car with a gallon of Evercoat's Slick Sand and am blocking it out now. I'm very happy with the way the Slick Sand layed down and it is very easy to sand and level. Then I will apply a Dupont sealer and finish by using their BC/CC system. He said he's done a number of Vettes this way with good results.
On the recommendation of the guy at the local paint shop, I've since sprayed the car with a gallon of Evercoat's Slick Sand and am blocking it out now. I'm very happy with the way the Slick Sand layed down and it is very easy to sand and level. Then I will apply a Dupont sealer and finish by using their BC/CC system. He said he's done a number of Vettes this way with good results.
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