mad_machine
mad_machine GRM+ Memberand SuperDork
12/6/09 2:16 a.m.

Been a long time since I painted a car.. and the last time I did, it was a fiat with chrome bumpers. I am hoping monday to have the body of my saab painted, but I still need to sand and prep the soft plastic covers for the bumpers.

I know I need a flex agent for the colour and clear coat.. but do I need it for the primer?

BoxheadTim
BoxheadTim GRM+ Memberand Reader
12/6/09 6:38 a.m.

I defer to the greater knowledge on this board but I think you do, yes, unless you're using special plastic primer which should work OK without a flex agent.

Then again, I might be talking out of my backside

White_and_Nerdy
White_and_Nerdy Reader
12/6/09 8:36 a.m.

If the primer doesn't stick to the bumper, nothing on top of it will will have a chance. Seems to me the primer is the most important part, and should have a flex agent, or be that special plastic primer.

Ironically, I've had 4 Saturns but never had to paint any plastic on any of them - and since their bodies are mostly plastic that's kind of amazing.

aussiesmg
aussiesmg SuperDork
12/6/09 4:13 p.m.

I found both a flexible plastic primer and bumper paint in aerosol cans at Advance Auto which has held up so far without issues

EvanB
EvanB GRM+ Memberand HalfDork
12/6/09 4:27 p.m.

When I painted my Miata I just wetsanded the bumpers and painted them with the same paint as the rest of the car, no flex additive. It has held up fine for the last four years.

socalwrench
socalwrench New Reader
12/6/09 10:35 p.m.

Scuff up the bumpers (sanding them of course), clean them (alcohol, thinner, and/or wax cloth), and paint. If there is a decently smooth layer of paint, a primer isn't necessary. How smooth you want the paint is up to you as you can sand and clean between coats.

For urethane bumpers- a flexible paint, such as bumper paint (aka polyurethane) is necessary.

YaNi
YaNi Reader
12/7/09 11:44 a.m.
socalwrench wrote: Scuff up the bumpers (sanding them of course), clean them (alcohol, thinner, and/or wax cloth), and paint. If there is a decently smooth layer of paint, a primer isn't necessary. How smooth you want the paint is up to you as you can sand and clean between coats. For urethane bumpers- a flexible paint, such as bumper paint (aka polyurethane) is necessary.

A flex agent is not necessary. Modern urethane paints will flex just fine. I have a friend who is a chemist for PPG tell me that.

Adhesion promoter, epoxy primer, high fill primer, epoxy primer, base, clear

dansxr2
dansxr2 Reader
12/7/09 1:16 p.m.

http://www.wmbarr.com/product.aspx?catid=1&prodid=72

We used this at our tech school body shop. Works well and is also a flex agent too.

pinchvalve
pinchvalve GRM+ Memberand SuperDork
12/7/09 1:21 p.m.

I can tell you this. Whatever Earl Schieb uses does not flex. I backed into a post last week and my bumper paint cracked like glass.

kreb
kreb GRM+ Memberand Dork
12/7/09 1:42 p.m.

What filler (If any) will do the trick? I can't imagine bondo cutting it.

kpm
kpm New Reader
12/7/09 1:53 p.m.
kreb wrote: What filler (If any) will do the trick? I can't imagine bondo cutting it.

Evercoat 411 Poly Flex flexible glazing putty works great.

Oh and +1 on the Bulldog adhesion promoter !!

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