1974 Lotus Europa

Anything goes in the world of fiberglass and plastic



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PostPosted: Wed Nov 05, 2014 6:24 pm
I have my car down to bare fiberglass. I removed six layers of material (primer+color+primer+color+primer+color) with 80 grit and a DA sander and did not find any gelcoat. There may have been a very thin layer of resin sprayed on the fiberglass after it came out of the mold, but no gelcoat. My question is: do I first apply a layer of 2K epoxy primer then multiple layers of polyester primer/surface then do the block sanding or do I skip the epoxy primer and go directly to the polyester primer/surface. My concern is fiberglass repair work telegraphing thru the primer and into the color/clear coats.

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PostPosted: Wed Nov 05, 2014 11:33 pm
This will probably end up over in our fiberglas section..... but here's my read on it. I checked and from everything I could dig up on Lotus it does appear they shot "something" like a gel coat into their molds first before doing layup. It's just about impossible to do production layups without using some type of uniform material that will allow the parts to be pulled cleanly from a mold. My guess is that this was the modern forerunner of what we now call a "sandable" gel coat. That material can be quite thin and you can blow through it fast with a sander. My thought at this point is, yes, seal that old fiberglas with the 2k epoxy and then get into your poly primer. AND after you get it guide coated and blocked out level consider doing a slightly thinner seal coat of your epoxy again. This should give you an almost impenetrable sandwich of dissimilar material to keep ghosting and printing out of your topcoats. Another step that I like to add in the middle is to let your poly primer coating cure out in sunlight for a few days before guide coating and blocking. You would be surprised how it can "shrink back." You want all that shrinking to be over with before you get into those topcoats.
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PostPosted: Wed Nov 05, 2014 11:41 pm
Thank you for your advice - exactly what I was looking for. Putting the car outside is probably not an option due to the coming of winter temps plus the car is sitting on a dolly (fiberglass shell + frame only) in my basement shop. My work area is maintained at 70 deg. F., so I guess I could let it sit there for some time - would a month be sufficient? I looked thru the 'fiberglass' section and didn't find anything that addressed my problem, but should have probably started there.

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PostPosted: Thu Nov 06, 2014 12:01 am
If you cannot get it into the sun, yes, leave it sit for at least a few weeks and a month wouldn't hurt if you can spare the time. My cousin, a professional pin stripe/ graphics guy once visited Boyd Coddington's studios out west and noticed an entire lot of cars next to the main building all covered in primers, bondo, etc. When he asked the shop manager what they were doing with them his comment was, "We're letting them shrink." Interesting, right???
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PostPosted: Thu Nov 06, 2014 4:18 pm
Darrel, what's your opinion of applying a coat of true gelcoat
on the bare fiberglass before the epoxy primer?
"If you can't move it, paint it." - U.S. Army

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PostPosted: Thu Nov 06, 2014 4:41 pm
I am just not big believer in doing the "aftermarket" style gel coat. Gel coats were designed to work in the molding process. For them to work properly in "open air"they must be modified with another additive package. Gel coats are indeed harder than regular auto paints however what we see with age is the "window pane" style cracking and spidering. Epoxy has much more flex and give to it. Actually most of the newer "sandable gel coats" are softer anyway compared to the old hard ones of yesteryear so what's the point. You might as well just get into your regular coatings process anyway. You can get some really pro opinions on this over at... http://www.fiberglast.com

Oh, and someone is just dead set on replacing a gel coat this is the stuff you need to make it cure right in open air....
http://www.fibreglast.com/product/Durat ... /Gel_Coats
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PostPosted: Thu Nov 06, 2014 6:28 pm
Thanks for the info Darrel. That makes sense about the
flexibility of epoxy vs the old style gelcoat.
"If you can't move it, paint it." - U.S. Army

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PostPosted: Thu Nov 06, 2014 11:18 pm
Yeah, this is a subject I think I've gone full circle on in the last 10 years. I was always convinced that "harder" was better when it came to coatings and fiberglas. But the reality of stone chips over those years changed my mine. I think a more flexible surface treatment is more important on fiberglas than it is on the metals most guys work here....
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PostPosted: Thu Oct 15, 2015 7:57 pm
Darrell,

I have two coats of black 2-part epoxy over the bare fiberglass then three coats of high build primer - both PPG products. I'm finding low areas after guide coating and block sanding the high build primer that are deep enough that they should probably be filled with body filler. Question - can I apply the body filler over the high build primer or do I need to go down to the black epoxy or, deeper yet, to the bare fiberglass.



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PostPosted: Thu Oct 15, 2015 8:25 pm
Filler is not to be applied over primer, but over epoxy. Standard procedure is to obtain a virtually straight panel prior to build primer.

Hey Darrel, has your rep spoken with you about Evercoat Fiberfill when making the rounds? He mentioned it to me for 'glass mods on trike bodies but I never tried it.
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