New bumper cover! primered?
#17
Rennlist Member
We already did boobies. I think all that is left if feet. I suppose we could do faces or even hairdos, but there might be something erotic about feet.
#18
I just went through the process of painting my front bumper. It took 3 tries to get it right. My mistake was trying to get it too perfect. I used an extremely thin layer of bondo and high build primer to eliminate the waves in the bumper. All told maybe a 1/32 of an inch in a few places. I used flex additive in the paint/primer. It looked great for a few months. Then two cracks appeared and the paint began to peel up along them. I thought it was a surface prep problem. So I sanded out the cracks and filled them in again this time using an adhesion promoter. Again it cracked! I just could not take this anymore and I swapped the bumper cover from another car. I did not do any filling on the new cover. I just sanded and primed the factory paint that was already there. I was careful not to sand through to the plastic. So far, it is looking great. Although, the cover has slight waves in the plastic. It is not really noticeable almost all of the cars are slight wavy.
Also, the flex additive is unnecessary for our cars because we don't need to bend the bumpers much to install them. Read the fine print on the bottle. It only delays the hardening of the paint so the bumpers can be installed without cracking. It is a common belief that the flex agent provides long term flexibility. This was pointed put to me by a real pro that helped me with my bumper cover.
There are epoxy fillers that bond to plastic that might work. And adhesion promoters that help bonding to plastic if you need to fair the surface. I must admit that when the bumper is perfect the car looks really sharp.
Also, the flex additive is unnecessary for our cars because we don't need to bend the bumpers much to install them. Read the fine print on the bottle. It only delays the hardening of the paint so the bumpers can be installed without cracking. It is a common belief that the flex agent provides long term flexibility. This was pointed put to me by a real pro that helped me with my bumper cover.
There are epoxy fillers that bond to plastic that might work. And adhesion promoters that help bonding to plastic if you need to fair the surface. I must admit that when the bumper is perfect the car looks really sharp.
#20
Burning Brakes
Join Date: Oct 2008
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Yeah, I just sanded mine until there was no flaking, and I shot paint right over it. It's been more than a year and no sign of failure of the coating. Mine was also newly purchased though, so YMMV
#21
Neil, a couple of things, never use a stiffer material on top the base material, there is special bumper bar filler which I did use as straight from the factory the early bars particulary have kinks etc. The filler is difficult to sand and most won't be able to do it properly, it does take a fair bit of experience or good advice.
The flex add never actually hardens, these bars are very flexible, Glasurit, the factory paint and one of the best paints in the world recommends differing amounts of flex add or "softface" for differing stiffness bars. Or at least they did when I did my jobs. Now before I bothered to do all jobs myself on my cars. The pro painter screwed up the job by not using the flex add in the primer! This earned him some rebuking by me and his boss as the job ended up free and a pain in the **** for yours truly.
The flex add is not just to put the bars on, my wife happened run my Porsche into another one of my cars, the bar was literally damaged, needed the heat gun on it to straighten it but the paint never cracked and 5 years on is still fine!
Mike take who's advice you believe, I will garantee you I am correct on this issue, been there done that. I can find the name of the plastic bar filler if you are going to get fussy with it.
Cheers Greg
By Neil Forn
The flex add never actually hardens, these bars are very flexible, Glasurit, the factory paint and one of the best paints in the world recommends differing amounts of flex add or "softface" for differing stiffness bars. Or at least they did when I did my jobs. Now before I bothered to do all jobs myself on my cars. The pro painter screwed up the job by not using the flex add in the primer! This earned him some rebuking by me and his boss as the job ended up free and a pain in the **** for yours truly.
The flex add is not just to put the bars on, my wife happened run my Porsche into another one of my cars, the bar was literally damaged, needed the heat gun on it to straighten it but the paint never cracked and 5 years on is still fine!
Mike take who's advice you believe, I will garantee you I am correct on this issue, been there done that. I can find the name of the plastic bar filler if you are going to get fussy with it.
Cheers Greg
By Neil Forn
I just went through the process of painting my front bumper. It took 3 tries to get it right. My mistake was trying to get it too perfect. I used an extremely thin layer of bondo and high build primer to eliminate the waves in the bumper. All told maybe a 1/32 of an inch in a few places. I used flex additive in the paint/primer. It looked great for a few months. Then two cracks appeared and the paint began to peel up along them. I thought it was a surface prep problem. So I sanded out the cracks and filled them in again this time using an adhesion promoter. Again it cracked! I just could not take this anymore and I swapped the bumper cover from another car. I did not do any filling on the new cover. I just sanded and primed the factory paint that was already there. I was careful not to sand through to the plastic. So far, it is looking great. Although, the cover has slight waves in the plastic. It is not really noticeable almost all of the cars are slight wavy.
Also, the flex additive is unnecessary for our cars because we don't need to bend the bumpers much to install them. Read the fine print on the bottle. It only delays the hardening of the paint so the bumpers can be installed without cracking. It is a common belief that the flex agent provides long term flexibility. This was pointed put to me by a real pro that helped me with my bumper cover.
There are epoxy fillers that bond to plastic that might work. And adhesion promoters that help bonding to plastic if you need to fair the surface. I must admit that when the bumper is perfect the car looks really sharp.
Also, the flex additive is unnecessary for our cars because we don't need to bend the bumpers much to install them. Read the fine print on the bottle. It only delays the hardening of the paint so the bumpers can be installed without cracking. It is a common belief that the flex agent provides long term flexibility. This was pointed put to me by a real pro that helped me with my bumper cover.
There are epoxy fillers that bond to plastic that might work. And adhesion promoters that help bonding to plastic if you need to fair the surface. I must admit that when the bumper is perfect the car looks really sharp.
#23
Drifting
Almost every filler on the market is polyester, not epoxy.
The reason you had problems with the filler is probably because you used the wrong type, and you didn't apply adhesion promoter prior to using the filler. Evercoat makes a product called "Poly-flex" which is a filler for flexible materials. But I don't know if it's even flexible enough for 928 bumpers. Bumper covers turn up on e-bay all the time, especially rears. I wouldn't waste my time with one that was bad enough to require filler.
If the Glasurit technical manual says I need to use flex additive, and this tech manual was written for a product that was developed in a multi-million dollar facility, by a person with a master's in chemical engineering, who would I be better taking advice from? The engineer, or the high school drop out whose primary concerns are getting to happy hour on time and squeezing a few extra pennies of profit?
Last edited by JHowell37; 08-12-2010 at 06:45 AM.
#24
Drifting
I painted my own and used Glasurit. Everything you've said is spot on. The only thing I'll add is that virtually all of the paint companies have specific processes for painting plastics that are unique to their product lines. If you don't stick to their procedure exactly as it is outlined, it will cause problems down the road.
#26
Three Wheelin'
Thread Starter
The grey just seems so "American". I would have expected some weird primer color from Porsche.
Jim, you yourself could have sold this! I feel it should remain in the original box for posterity, like a cabbage page doll but I have an 'idea' for it!
Jim, you yourself could have sold this! I feel it should remain in the original box for posterity, like a cabbage page doll but I have an 'idea' for it!
#27
Intermediate
Join Date: Jul 2010
Location: Svelvik, Norway
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Maybe a strange question, but...
Is there a DYI thread about painting plastic parts?
As you see here, my bumper looks BAD... After somebody tried to do the paint job "at home"
Please keep in mind: Painting a car in Norway (or Scandinavia) is VERY expensive :-(
Is there a DYI thread about painting plastic parts?
As you see here, my bumper looks BAD... After somebody tried to do the paint job "at home"
Please keep in mind: Painting a car in Norway (or Scandinavia) is VERY expensive :-(
#28
Three Wheelin'
Thread Starter
Greg, what bar filler did you use? It sounds like an epoxy, no?
Thanks everyone for the advice!
#29
Drifting
I'm sure someone will try to argue with me on this, but you don't need a flex additive as long as you use the correct primer and scuff the bumper well enough. Southern Polyurethanes has a fabulous Epoxy Primer that works perfectly on our bumpers and is flexible enough to prevent paint from chipping.
On my race car, I DA'ed the front bumper bare with 60 grit and sprayed with epoxy primer. I even put filler on top of the epoxy primer to fill the headlight washer holes after they were plastic-welded shut. Guess what? Two years and 10 or so track events later (with several hits on the bumper during that period and a splitter partially mounted to the bumper cover), there are no cracks.
On my race car, I DA'ed the front bumper bare with 60 grit and sprayed with epoxy primer. I even put filler on top of the epoxy primer to fill the headlight washer holes after they were plastic-welded shut. Guess what? Two years and 10 or so track events later (with several hits on the bumper during that period and a splitter partially mounted to the bumper cover), there are no cracks.
#30
Drifting
I'm sure someone will try to argue with me on this, but you don't need a flex additive as long as you use the correct primer and scuff the bumper well enough. Southern Polyurethanes has a fabulous Epoxy Primer that works perfectly on our bumpers and is flexible enough to prevent paint from chipping.
On my race car, I DA'ed the front bumper bare with 60 grit and sprayed with epoxy primer. I even put filler on top of the epoxy primer to fill the headlight washer holes after they were plastic-welded shut. Guess what? Two years and 10 or so track events later (with several hits on the bumper during that period and a splitter partially mounted to the bumper cover), there are no cracks.