Fiberglass question
 

I noticed that when i did the fiberglass bumper that it chip like crazy almost to the point that in 2 days of having it on my car it looked terrible. I am just wondering if anyone else experienced this. The side skirts wheel well area also chipped like crazy from the rocks shooting off the tires. Is there any special way to paint fiberglass bumpers or side skirts where the paint actually doesn't chip away at such a high rate that the bumper is almost down to the orginal color..What is the oem bumper made out of plastic? The worst part of the story is that my car is not even a daily driver but i drove it when it has the kit on it for 2 days and then almost cried when i saw my front bumper and side skirts.

Hi,

The OEM Bumper covers are made of Urethane a pliable plastic which can absorb the energy of the impact and then return to it's normal shape. The fibreglass parts are attractive because they can be made easily in a mold, and can be relatively thin, making the piece cheaper to produce and cheaper to buy. But, bye-and-large, they are less durable.

Fibreglass is made up of resins with short glass firbres imbedded into it. It is fairly strong, but does not mold to a smooth, paintable surface. If the component was Fibreglass alone, with the weave (Glass fibres) just below the surface, painting it would leave a very irregular, rough surface. So, most fibreglass components are usually coated with a polyester resin called Gel Coat. Gell Coat is usually sprayed into the mold first (after a mold release agent is applied directly to the mold such as a wax or silicone, so the part will separate from the mold once cured) and gives the component a smooth, paintable surface. This Gel Coat, though smooth and relatively durable, is prone to dings and scratches. Unfortunately, what you describe is characteristic of the Gel Coat pitting, in addition to losing the paint.

Gel Coat is somewhat difficult to work with and the solvents used in it can be toxic. In order to repair this piece, you'd first need to fill the pits, sand it smooth and then apply the paint. Bondo or other filler can be used, but usually makes a poor bond, so with time, it's likely to come loose. An old trick used by guys with fibreglass cars such as TVRs and Lotus, use a plain two-part epoxy to fill the pits. Epoxy has several advantages. First, it cures fairly quickly, whereas Gel Coat and Bondo continue to off-gas their solvents for days, causing a delay in painting the piece. Epoxy also has very little (if any) shrinkage, so multiple applications are usually unecessary. It can be roughed in and stays flexible for some time before curing. Then, it can be sanded smooth. It bonds well with the piece and accepts paint well too.

There are a number of rubberized coatings on the market, which are paintable. These are often used on rocker panels and areas prone to stone chips. The problem is that these tend to be rough and aren't easily smoothed out to paint quality.

So, unless you don't mind an irregular finish, the fibreglass piece will require some fairly regular maintenance. The Air Dam on my Lotus Esprit experiences much of what you are. But, it is very thick, and so can withstand more abuse. I use the epoxy method to repair it and and then paint it w/ touch-up paint. This looks pretty good. But, every 3-4 yrs., the accumulation of these chips makes it necessary to strip and sand the piece and do an entire repaint. This is the downside of the cheaper fibreglass pieces out there...

Happy Motoring!... Jim'99

While I 100% agree with your assessment of the "fiberglass question," Jim, I must say that I believe that something had to have been done wrong in order for it to only last two days! Obviously we'd need to see pics before being able to effectivly diagnose it, but c'mon, the clearcoat should have taken the abuse from two days worth of driving..

My guess is that something wasn't applied right..... Although if the question was about 3 or 4 months after you put the glass on, I think Jim's response would be right on..

How about some pics?

hey i have a question? can you mold a fiberglass front lip onto the poly/ plastic front bumper?

Hi,

The point you make is well taken, but consider what kind of driving was done in just those two days. You could put tissue paper on the Bumper and in just two days in my neck of the woods, you would be hard pressed to damage it significantly in such little time.

For any material to have been exposed to so much chipping in only two days, the lister must have been doing donuts in a Gravel Pit, or tailgating a DOT Sanding truck.

The truth is, Fibreglass reproduction pieces are cheap, and they are cheap, cheaply made that is which is why they are so inexpensive to begin with. This is the only way they can compete in the marketplace with Urethane parts. Proving the addages that You get what you pay for and Cheap is rarely, if ever, cheap.

This will be a constant maintenance headache for the Lister, unless he swaps the fibreglass part for the more expensive (though maybe not so in the long run) Urethane one...

Happy Motoring!... Jim'99

I think the whole question is why doesnt paint stick to fiberglass. There have been some reasons given, but im not convinced with the gel coat or the lack of flexibility of the fiberglass. Why wouldnt putting extra primer on the fiberglass make it behave like urethane? I know a tiny rock isnt going to make urethane bend to absorb the blow, but it also doesnt take the paint off, My 8 year old bumper looked pretty darn great for original paint. (all orginal paint car btw, except the new bumper, diffusers, bumperettes, and soon to be side skirts, lol)

Hi,

I hear what you're saying, but more primer probably isn't going to do it. The thing is, you do not want a lot of primer underneath. This will tend to protect the Gel Coat much more than the top color coat.

Flexibility in the top color coat is the key, and that may be the issue - too hard a color coat. The new self-healing paints now offered (specifically by Nissan) are fairly soft and so can absorb the impact and flow to restore that paint which is pushed away by the impact. It may be worth exploring this possibility with a Paint Guy, I'm sure these paints are available aftermarket to support the Bodywork Repair Industry...

Happy Motoring!... Jim'99

the pictures i have are not going to show too much of the chipping since i didn't take up close pictures. The fact is the bumper wasn't exposed to anything but normal highway driving . For what ever reason this is my second car with a fiberglass bumper and kinda of the same results.

I have fiberglass parts on my car. Front bumper and side skirts. I haven't noticed anything different as far as the chipping of the paint goes on my bumper compared to the original O.E.M. bumper. I think it all has to do with how well the bumper is painted. I've had mine on since last October of 06. I have no chips on my side skirts and very little on the front bumper. I go to car shows all the time and they aren't even that noticable. I just use touch up paint where needed. I only have 3-4 that are any bigger than a pin-head size on the front. Again, I think it has to do with a quality prep and paint job for best results. I do know that the painter told me he added "flex-agent" to the paint when it was applied, and they added 2 coats of clear gel coat instead of the regular amount. Hope this helps! :cheers:

I don't know anything about painting but I am curious if what I was told a few years back is correct or not. I had a black Lincoln LS a few years back and I was considering having the entire front bumper repainted due to rock chips. When I took it into the body shop he said it was probably better if they simply did some touch up work versus repaint the entire bumper. His reasoning was that the paint from the factory is a much more durable paint than what he could put on.

Is there any truth to this? Why wouldn't a body shop be able to apply the same products as the factory?

:confused:

Hi,

There is truth to it. EPA requiremants have made most manufacturers switch to electrostatic paints. Instead of applying liquid paint (with all it's nasty solvents, etc.) the paint now applied is more similar to powdercoat. The Paint particles acquire a positive charge (+) when the leave the spray gun, the Body is negatively charged (-). Since opposites do attract, the paint adheres to the body which is then liquified and cured in either an IR or UV oven. This why Orange Peel is so much more prevelant in new car finishes today than in the past.

A Body shop is neither required to have, nor can they afford to purchase, this technology, and so continue to use solvent based paints. Still, these should be more than fine in matching a factory paintjob if done carefully and correctly. Hope this helps...

Happy Motoring!... Jim'99