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samzhot240

Prep for air dam

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So I previously painted my fiberglass air dam that I purchased from Motrosport and for the first week or so it looked great, but despite purchasing the surface prep kits that was suposed to keep the paint from cracking under the normal flexing one might encounter the paint began popping right off. I was equally confused when I began scraping it off this winter and the primer seemed very well adhered. This time I intend on doing it right because I'm painting it orange to match the rest of the car and it will be a lot more obvious if the cracking starts again. Basically the cost doesn't matter this time as long it can be done at home because I'm just that kind of girl. So if anyone has any tips please help me out, I had a bar for reinforcement to keep the flex to a minimal but it really was in vain.

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I'm far from a paint expert, but I'd guess that in addition to the normal prep work, you might also want to put a flex agent in the paint.

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Arne hit it on the head, you will need to add Flex Agent to the paint in order to ensure that it will not crack readily. Go to your regular auto paint store and use that wording, and if they look at you funny, tell them it's so you can paint a rubber bumper. In fact, you could probably get them to do the flex agent and put it into a spray can for you all in one shot.

Next, that the paint chipped off the primer without removing the primer may have been due to, a) too thick a coat of primer, B) no sanding on the primer to accept the paint, c) incompatible primer / paint (i.e. lacquer paint on enamel (reducer based) primer, or lastly, d) paint on top of uncured primer (not enough time).

Hope that helps.

E

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You describe it as a "surface prep kit" that was supplied by Motorsport. It should have come with an instruction sheet and also should have been up to the task. It sounds to me that the primer went on fine, but there is an adhesion problem. Out of Enriques 4 possible causes I would first rule out (a) if the primer remained intact. (B) is a real possibility and also your fault if you didn't follow the instructions that came with the kit. © would be the fault of Motorsport supplying a sub-standard kit. (d) is also a possibility and again should have been covered in the instructions. The only other things I can think of off hand are the temperature at the time of application and extreme flexing or bumping onto curbing. I don't know where you live or the weather conditions, but I have seen these things shattered easily in the severe cold. Other than us guessing the cause, all you can do now is follow Enriques advise and have the pros at the paint dealer set you up properly with the correct materials and instructions. Good Luck

PS-Something tells me we are going to hear more about (a):laugh:

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I bought A fiberglass airdam from Motorsport and the Body Shop that did the paint/body on my 71 240 said it needed some serious prep to get it so the paint wont crack. They said 8 hours of their time to get it perfect because of the little cracks in the gell coat of the fiberglass. I understood what they were saying, but 8 hours seemed ridiculous to me. I took it to a fiberglass specialist and they did it in three hours. If you want it perfect I suggest you find someone who can do it well. Mine turned out perfect but cost me a lot. You can look at my pictures to see it.

K

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OK, I want to look at kcoke's pictures. What's the easy way to do that? Remember when we could just click on a USER NAME and then click on that user's GALLERY in their PROFILE?

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So I should be adding a flex agent right into the paint and do I add it to the topcoat as well Because I plan to run the black Stripes right down the air dam so I'll have to do the topcoat as well. It couldn't have been the weather that caused the cracking because I don't drive the car before April (whenever the snow melts) or after October( whenever they predict frost or snow). It was probably a combination of human error and lack of knowlegde on the topic so I plan to take it to an auto tech guy to see what he can recommend to me cause I really want it to come out perfect(or as close to it). Thanks for the tips this site was the best thing I ever came upon since I bought my car. My dad's pretty good with this stuff but me being only 15 at the time and his rustyness on the painting and restoration part I couln't have half the car without it. woo-hoo!

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If you are using paint that you have on hand already, Id suggest getting a product such as Kleenstrip tie coat to mix into the paint. Just make sure it is compatible with your paint. If you have not bought the paint yet, your paint supplier will offer the best solution for the paints they sell. It is a definite adhesion problem which goes hand in hand with a paints ability to flex. Pay particular attention to the paint prep. First use a good wax & grease remover before doing anything. You do not want to sand any contaniments into the surface.

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flex agent is a temporary thing. What I mean by that is after a while its benfits go away. Flex additive is basiucally for reinstallation of parts after they have been painted. If you flex paint far enoughm it is going to crack, period. Fiberglass needs nothing special to prep it compared with steel. A prep kit for glass is a rip off. Prep it the same way you would steel, meaning good mechanical adhesion by proper sanding, followed by epoxy primer.

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