Paint Detailing Question: Fiberglass

[62BT7]

My car has fiberglass fenders, installed by my PO. I know, heresy, but they are very well done, lighter than metal, no corrosion, etc. I've decided to stick with them at least for the time being. I've thought about doing a new paint job next spring, but walking around the car more carefully I'm now convinced that with some touch up paint, wet sanding, light polishing compound, sealer/polish, and wax I could have a close to excellent finish for maybe $100 out of pocket, of course not including new gaskets/grommets, parts, chroming bumpers, etc. The only problem I have is the left rear fender/quarter panel. My PO apparently backed into something lightly and it has no cracking of the panel or paint chipping, but has very noticeable "spider webbing" or "starring," typical of fiberglass low impact contacts. Just hairline cracks of the paint, but visible 5 feet away. I just washed the section, used Meguairs (sp?) Scratch X polish followed by carnuba wax, no real improvement to the hairline cracks (but the other paint looks great!) Has anyone ever repaired/detailed such a problem? A paint job is the obvious fix but a really good one is pricey, and a spot job poses other paint matching problems. I have the time to detail it well, and spending $100-200 vs. a few thousand disturbs me. The other paint is pretty good. Ideas? Thanks,
-Tom

 

[Keoke]

Hi Tom, Generally fibre glass parts are not painted tyey have what is known as a gel coat finish. Repairing cracks in gel coat requires an esperienced person. Painting over gel coat in good conditin is not much different than paint ing over a metalic surface. Visit a Corvette repair shop and see how they do it.--Fwiw--Keoke

 

[nevets]

Try posting your question on the Lotus forum...someone there is likely to have experience with your problem.

 

[JamesWilson]

Rod and Custom Magazine Article might provide some useful information. A lot of information can be googled- soem of it might even be useful... /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

I've got a fiberglass boot lid on my Jensen-Healey and it looks good and indistinguishable from an original. A friend runs a Healey that was formerly used for hill-climbs with fiberglass front wings. They've been painted and while some care and attention is needed they can be painted readily enough.

 

[HEALEYJAG]

Have had quite a few vettes in the past..painted about 6.. The "cracked finish" on the fender has to be sanded or ground down to so the is no visible imperfections. This sounds like a "Surface " problem. No fiberglass should be needed for the repair.

A good plastic filler can be used to reshape the cavity..be sure to allow ample time for shrinkage. I have feathered in my e-type paint many times with excellent results. A COMPETANT painter can do the same for you , especially if it is not metallic..

Good Luck:

Pete

 

[pan]

Sorry Keoke but I wish to correct you. Fibreglass parts do indeed have an exterior surface that is gelcoat but this is rarely left unpainted when parts are made for the auto replacement industry. It is very difficult to match the paint colour with the gelcoat. Trailer boats are usually left unpainted.
Tom, I offered some advice recently on this forum to assist repair of a hardtop.The star crazing you describe might only be in the gelcoat but it is more likely to have damaged the sub-strate laminate. A cosmetic repair will soon deteriorate. You need to inspect the inside surface of the panel. Look for an area that is lighter in colour than the surrounding material. This indicates that the glass strands have delaminated from the polyester. It is still easy to repair.
One of the main advantages with this material is its memory. After damage it resumes its original shape. This is why crash helmets are not to be used again after any impact.
I once saw a Lotus Elite (early model with fibreglass monocoque) side-swipe an Armco Barrier at speed during an Historic race. I swear the car deformed to half its normal width before bouncing off. Later in the pits, I inspected the car which now didn't look too bad, but the integrity of the structure was destroyed.
Alwyn

 

[Keoke]

What a wast of time Pan. We gelcoat the whole car!. If it gets scratched up we use a computer color match sytem, course 'Matcha' in the paint shop is better than the computer.---Keoke------- /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

 

[vette]

Hi Tom, My Healey also has fibre glass fenders. I am very happy with them and of course am not concerned with concours judging. Of course my 'other' car has fibre glass all over it. I have painted it, repaired it and blended it a few times over the last 20 years as well as other cars. Obviously a damaged area, like all damage, must be taken down to the point where the damage is no longer there. Sand thru the cracks either by hand or with a Dual Action sander until the crack is no longer there. If you get to the fibre glass matt or fibre before the crack is gone then that means the crack is into the glass and that will have to be repaired. Once you get that sanded back, you can re-gel it. Or you can also use Resin. If you have cut into the fibre matting, might best to layer alittle matt and resin together to bring it back level. Aways finish with with a good layer of Resin as you will sand this back down to the correct contour. IF THE CRACK GOES ALL THE WAY THRU THE PANEL, YOU WILL HAVE TO USE RESIN AND MATTING. AND YOU WILL HAVE TO DO THE SAME TO THE UNDER SIDE FOR STRENGTH. As far as final finishing, do the same as you would do on a metal panel. Use very good quality primer and/or epoxy primer as the new matt has an easy ability to show thru cheaper products. This sounds tedious, but I find that is is not much different than welding in a good fix on a metal unit. You must still take care of the welds and treat the back. If you are doing any sanding at all, which you do have to do to fix a crack, you are going to be into doing some colour matching to make the panel look right. This means at the minimum to blend out the paint with a spray gun or an air brush. Depending on size of area to be covered. Then wet sanding and buffing.
Having said all of this, if you are so lucky to have such a shallow crack that it is not deeper than about half the thickness of the colour paint. then you might be lucky enough to repair it by wet sanding it with 1500 or 2000 grit paper and buffing it back to luster. Stars and Spider cracks are usually much deeper than that.
Hope is helps.
Dave C.

 

[Keoke]

Yep Vette sounds like you know how to do it. Most of the time though we tend not use glass resin in the repairs it is much stronger and resists cracking if epoxy resin is used. Epoxy resin does not go in to the glass range and crack like glass resin tends to do.---Keoke

 

[pan]

Hi, all you amateur fibreglassers!
Composite products are usually formed in a mould, working from the outside, in. First the gelcoat is applied to the mould with a paintbrush or spraying. Once set, the glass/ polyester resin laminate is applied, again by pot & brush, or chopper/spray gun. Resin/glass ratio is critical, no more than 2 of resin to 1 of glass. Use scales to achieve this if using the pot & brush method. Chopper guns should be calibrated. Once cured, the product is released from the mould.
If the product (in this case an auto panel) is lightly damaged and only shows cracking in the gelcoat but no deforming of the shape, the best repair is to start on the inside, grind away most of the de-laminated glass & resin (mindful of the nasty dust thus created!)replace the laminate, THEN work on the outside to restore the cosmetic appearance. Correctly applied polyester will do a better repair to a polyester resin/glass composite than epoxy.
I have seen many FRP cars and the best from the standpoint of FRP construction is the Studebaker Avanti, closely followed by the Chevrolet Corvette. They make '60s Lotus look like backyard specials. (from the '70s Lotus have used resin-injection methods).
Anyway, this is an Austin-Healey site! What are we doing talking about plastics?
Alwyn

 

[Keoke]

My goodness Pan! You did go on a bit Huh.However, it is gratifying to know that you recognise a bonafide pair of amatuer "fibreglassers" when you hear them.---Regards--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

 

[vette]

That's right Keoke, but we get err done.
Pan, might I ask, what is the difference whether you start on the inside or the outside your still doing both sides. Yes I agree with you that the polyester resins and puttys are the way to go in a repair. I was referring to Epoxy primer earlier to resist bleed thru.
Obviouly, I'm alittle partial to corvettes. [censored] good body. I did read somewhere many years ago that the corvette body is one of the thickest and strongest of all. The car would actually be lighter if they had built it out of metal. The Healey fibre glass replacement parts are rather thin and crude. But that's just another challenge to enjoy. They don't rust, and they look good if done right.
Cheers, Dave C.

 

[pan]

Keoke, I suppose when it comes to composites, I am a bit like Dave Russell (whose knowledge I admire). I would even admit to being an expert, if only that didn't indicate that I am "a has-been" (ex) or a drip under pressure (-spurt).
Dave, In my post I referred to the material having a "memory". After a small impact, the stuff returns to its original shape. By working from the inside you don't interfere with that shape and by not removing the original gel-coat, restoring the outside surface is made easier. If you remove all the outer surface you have no datum or reference point to what the shape was. I have seen plenty of repairs that have unsightly bulges where too much glass & resin have been applied, then the repairer got fed up with sanding the itchy stuff back. Working on the inside, you can build up the thickness as much as you like.
Alwyn

 

[Keoke]

Pan, seems like you be telling me there is more than one way to skin a cat !!----Keoke--AZ-- /bcforum/images/%%GRAEMLIN_URL%%/cowboy.gif

 

[vette]

Ok Pan, I recognize you point of view and it may be the supior way to go about it. But in all practicality I don't think many shops are working it completely from the back side out. And their is alot of custom glass work going on. If the craftsman doesn't get the contour right he better find another line of work. By the way, if the crack is all the way thru, seems to me your going to have to remove some gel coat. If your workmanship is so finese that you can work just to the milage of the gel coat and still repair a crack all the way thru, then I congratulate you. And I don't doubt that you can, but I suspect that your energy spent in that aproach doesn't yield any more durable or astetic repair than just grinding it down and rebuilding the material. But as I said, I congratulate you on that method and would be endulged to be able to learn your system for it surely contributes to the greater knowledge of working with fibreglass.