My rear bumper has been hit and there are hair line cracks in the paint. The car has been repainted (previous to me buying it) and I suspect they did not use any flex additive. Can you suggest the best methods of stripping the paint?

 

Flex agents only last a couple weeks before they cure out. And there is a section on the forum under TECH TIPS that can help you strip that bumper.

 

Yep. :yesnod:

 

Are you saying that after a couple of weeks, the flex agent is gone and the paint is as brittle as if it never had flex agent in it? I used to work in a Napa where we mixed paints, and I have done a little body and paint work in the past. (20 to 25 years ago) We used to sell the flex additive to put in acrylic laquer for bumper repair. I always thought it kept the paint flexable for the life of the paint. If this has changed or if I have always been wrong, please tell me. Also if you could, please recomnend a chemical stripper that is useable with the bumper. In the teach tips, under bumper repair, it only address sanding out cracks in the clear coat. In the section on stripping paint it does not recomnend the chemical stripper (styrpt ease?) for the bumper. They say to use one that is compatable for the bumper. Could you make some recomnendations on what to use on the bumper and how well they work. As I stated earlier the car has been painted before, and I believe the paint is to thick. Thanks for your help.

 

Yes, the flex agents last only a couple weeks. If it was my car here is what I would do. 1 You are saying that there is a build up or paint on the car. I would not use any chemical strippers on it. There is not that much SQ. footage there so I would hand sand it. Start with some180\ 220 grit and then 320 and 400 wet\dry Then get you some good epoxy primer sealer. Use some urethane paint on it. No flex agent. I painted my car 8 month ago using PPG DBU series and I can go and push on the bumper and the paint flexes with the bumpers. Urethane stays flexible for many yrs. I hand sanded my whole car in like 60 hours. So that back bumper should take 5-6 hours.

 

Thanks for your reply. I guess I was trying to get out of that elbow use!! I will try sanding by hand first. Just thought a liquid stripper would be easier, exspecially around the lights and lettering. But I dont want anything that is going to effect the bumper itself. So its hand sanding I try. Thanks again.

 

I have had to touch up my bumper covers so I have just sanded it down to the rubber. The last time I had the hole thing stripped I took it to the chevy dealer, they get about 400.00 if I remember correctly.

I want to elaborate on one item and see if anyone else has any knowledge. Your comment on the flex additive. I have been painting my vehicles for 20 years and I have always used flex addivitve in the rubber areas as the intent of it was to be flexative for the life of the paint. I have used in on race cars as when the aluminum bodies get pushed in the paint does not crack when you push the damaged area back. On some of my larger accidents I have taken of the paint with a scraper and it did seem to still be flexible. The bottom photo is an example on the car in the background. The right front fender was mangled beyond repair so I cut it off just above the center line of the tire. Even in the mangled portion of the fender (that hit the trash can), none of the paint cracked.

Now the last time I bought flex additive to paint my vette I was told the same thing. That the agent is only good for a couple of weeks and the primary intent is for the paint to remain flexible while the mechanic puts the car parts back together. Then it just goes away. Has flex additive changed over the years? anyone...

 

IMHO this is :bs I managed a shop for about 8 years and have never heard of this. I have even been to paint school and never heard of this.
Either this opinion he has is for one specific paint line or the info is FALSE!
As far as the refinishing the bumper just hit it with some 220 grit then 320 and finally wet sand it with 500 or 600 grit wet sand paper. (always)Seal it (always)prime and then paint it! Call it done. Flex goes in everything not just sealer or primer but all sealer, primer, and paint.

Go to the Paint manufactures web page and DO what the manufacture says to not void the warranty.


Some of the paint advice I have seen in some of these threds is just plan ignorant!




[Modified by blk91, 3:43 PM 1/23/2002]

 

you could have it media blasted. then prime & repaint it. :cheers:

 

your correct, I my experience and it's workewd is the PPC Concept, hardner and reducer and it worked perfectly.. this same mix can be shot on the car also, this is a very easy to apply single stage operation, no clear required. I have used it for bumpers and door jambs. The flex agent story goes back to the origin of flexable bumpers. Go by what the auto paint supply store or manufacturer says. There is more misinformation out there by so called experts.

 

I've been in the paint and body business for several years now. I can tell you that flex additive lasts a lot longer than 2 weeks. I was always curious in the past about this and decided to test it. I painted a rear bumper and used flex additive. A year later I removed the bumper off that same car to go to a different style bumper, I decided to give it a try. I twisted the hell out of that bumper and put it in all sorts of kinked up positions. Never cracked

 

Use a good urethane and you wont have to loss sleep at night. Urethane STAYS flexible for the life of the paint job!!

 

Once the flex additive is in the paint it is always in there. Assuming you take care of the paint it will last years, not 10 days. My suggestion too you is go with a high quality paint like Spes Hecker or Sikkens. I've used DuPont with good results also, but I did get some cracks that are in the paint. You will pay more for these paints but they are worth it. Also stay with the base/clear combo and use the recommended flex agent.
Justin

 

More incorrect info here! If this was the case you would not need the flex additive.

I went to school at the Sikkens location in Orange County. Sikkens as stated above is one of the VERY BEST! I can verify they are a Top Notch Company that stands by they're product!




[Modified by 01NHRA, 10:03 PM 1/23/2002]

 

This is good and I am glad I brought this up again off the original post. The person who told me the flex was only good for 2 weeks was the owner of the darn paint store. The next time it get rear-ended, I do believe I will question this further. Mine has been smaked in the rear 3 times. I have a large magnet stuck in the gas tank.

Fun fact...the last time I painted this thing base coat/clear coat, I used a very cheap urethane paint called Omni (whatever). I mixed too much clear (without any flex additive). There was about an inch left in the bottom of the mixing bowl, so I let it sit for a month. I ended up with a one inch thick block of clear paint that looked and felt like rubber and you could fold it in half, bounce it on the floor.... However, that same month a pebble hit the hood and the clear coat chipped off in flakes. Now, I wish I had added the flex additive to this last paint job.

 

What does flex agents do? They slow down the curing time! Do you think urethane get hard? No, they are soft. That is why them scratch easy. Get a hold of your Local paint store and ask them. They know both ends of the whole ordeal.

 

More miss guided info. The design of the flex agent is to add flexability to the paint on the plastic parts on your car. The plastic parts move FLEX :eek: . Thus they came up with FLEX ADDITIVE to add flexability to the paint on the plastic parts on your car.

Pretty basic. One thing you will see in the paint and body business is there are a ton of hackers out there. The good shops keep they're shop very clean and tidy. As for the hackers... Just open your eyes :eek: and they're right there.

Body shops are like Doctors.....You should always get a second opinion....
Sometimes even a third. ;)

 

I also ran a body shop, and never heard about flex agents lasting only a few weeks. And I spent several weeks with the Sherwin Williams rep picking his brains about everything.