shep28

iTrader: (4)

Is adding flex to paint required when repainting bumper?



Here is the deal... filled in all the dents on my winter beater car and cut out the massive rust cancer on the quarter panels. I fabbed some patches using a vise and a metal brake and had the muffler shop weld them in. Ground the welds and filled in the patches to a perfect fit. I must say that patches turned out great

Scuffed up bumpers using a DA and 400grit sandpaper, degreased bumpers, and sprayed adhesion promoter x 2 coats.

I asked a bunch of people about adding flex additive to the base and clear for the bumpers. Some say that it is not needed and others say the I must use it.

What do you think? I do not want cracks or spider webbing.

also, can I use polyester putty to fill in a few gouges on the bumper? I figure that polyester will flex unlike bondo.

SMDLS1

iTrader: (9)

No it isn't, but recommended because the bumper does flex so if you hit some thing and bend it the paint will spiderweb.

DopeFedZ

iTrader: (34)

If you use the flex I think it will help a bit in reducing the amount of rock chips your front bumper will acquire over time.

shep28

iTrader: (4)

What about the putty?

Fogle07

iTrader: (5)

dont have to put the flex agent in it but not a bad idea. the putty is fine just make sure you put one coat of primer then sand it down then prime again.

Jeremiah

iTrader: (5)

Like stated earlier, its a good idea not only to insure against flex cracks but also helps quite a bit against rock chips. Also, be sure to use a compatible filler for the bumper holes, regular body filler will eventually crack from different expansion characteristics. I would suggest using 3M Automix #5885,
it is a rigid plastic repair specific for urithane bumper covers.

fasteddyss

iTrader: (1)

The only purpose of flex additive it to prevent paint damage during assembly of parts. This will not prevent chips. It dries out of the paint in a few days. almost no one uses it.

The main purpose of it now is to pump up repair bills at body shops.

I was a bodyman and am now an insurance adjuster.

Good luck!!

Jeremiah

iTrader: (5)

Sounds like an insurance adjuster,

I know for a fact that it "helps" to prevent rock chips, and it does not dry out of the paint in a few days.

parbreak

iTrader: (17)

BS. I use it everyday for my fuel rail covers and it's not to pump up anything. The amount used is neglible and for what it does is well worth the addition. It may not prevent rock chips but it goes a hell of a long way against preventing cracks in flexible parts, such as bumpers. Plus some flex additives such as Bulldog are also a tie-coat and an adhesion promoter which helps "tie" the coats together and prevent future peeling.

Also, just exactly how does a flex additive prevent "damage" when assembling parts? I guarantee you if I bump a freshly painted part against something it's not going to matter how much additive is in the paint. It's going to scratch. Probably a good thing you went into the insurance business.

99taws6

iTrader: (2)

I have been researching this subject since I am getting ready to paint my fairings on my motorcycle and what I have seen is right on track with what fasteddyss is saying. It seems that flex agent was commonly used before the newer paints came out. I have found many sites and manufacturers website FAQ's that say you do not need flex agent anymore. Most new paints from leading manufacturers come with flex agent already built in. I also found that it was used to allow new parts to flex during assembly and not crack.

I do not know for sure, just posting what research has yielded and gasteddyss is not off the wall with his statement.

FYI I am going to use it just for ***** n' grins..

NOBR8KSS

iTrader: (12)

My front bumper cover from the factory had a pretty decent paint job. It never chipped even with over 75,000 miles on the odometer.
A little over a year ago, someone ran into it in a parking lot and actually split the bumper near the hood and scratched the crap out of it. But the paint didn't crack or spiderweb.
GM repainted the bumper based on what my insurance company would pay them. They did not use the flex additive...told me it wasn't necessary because paints are better engineered now...BS.
That was 13 months ago. The paint is split in 3 places, has dozens of chips in it, and the clear coat is coming off the bumper under the drivers headlight. One month after the warranty expired!...so I now have to pay a professional a hell of a lot MORE money to strip, sand, prime, and repaint my recently repainted bumper.

I will never again listen to an "insurance adjuster"...why?... because they are in the business of making money. Insurance companies do not want to pay it back to you! They want to make a profit!

Listen to the enthusiasts on this site who are concerned about getting work done correctly...not cheaply.

Jeremiah

iTrader: (5)

Leading manufacturers like DuPont or PPG?

they still crack from flex just as easy as the older paints. I do paint and body work and have worked on some of the rarest/ most valuable cars out there,from Boyd Coddingtons Chezoom, the #38 ZL1 Camaro and Carrol Shelbys personal KR 500 Conv ect. Flex agent works and it should be used on any F body bumper cover. The newer covers on most cars are very rigid and dont require a flex agent, Anyone who has ever removed an F body bumper cover knows they are not rigid at all. I have worked with several painters who learned there lesson the hard way, one TA bumper returned with stress cracks only a couple of months after we painted it. The painter used paint stripper and ruined the cover and had to buy a new GM cover out of his own pocket, that was an expensive lesson.

Oh.. and this was with the latest and greatest PPG clear.

parbreak

iTrader: (17)

What he said!! Anyone who thinks they can paint a bumper or any other flexible body part without an ADDITIONAL flex additive and have it last is fooling themselves and will learn the hard way. Do all the research you want, but listen to experienced painters who work with this stuff everyday.

Bryan
parbreak

indoes

I have the answer for this one. I was at my local house of color today to get some paint for my bumper. This is what they recommended. With the primer I'm using (PPG NCP-280) and instead of using a flex agent in the paint I could use an adhesion promoter/flex agent (bulldog 3 in 1 something I'll check it when I get home) before priming and then primer, paint, then use flex agent in the clear coat. I don’t know if this will apply to your primer but if it’s a urethane compatible primer it should. This way you don’t have to use it in the paint. If you don't want to do it this way then yes use it in the paint, it’s insurance.