Flex Additive Question?
Thread Starter
Drifting
Joined: Jun 2005
Posts: 1,523
Likes: 1
From: grand prairie texas
Flex Additive Question?
I had the three coats of paint soda blasted off of my original urathane rear bumper cover which came out looking great but my question is when I primer it do I need to add a flex additive to the primer or just the base coat and clear coat or all three coats?
Racer
Joined: Dec 2005
Posts: 325
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From: Partlow VA
What brand paint are planning to use? PPG says no flex is needed if you use the DBU base coat/ clear coat. I had it on mine when a 18 wheeler hit me in traffic (twice) once he rolled into me the other his foot slipped off the clutch. It really made no differance had to replace the rear bumper anyway.
Drifting
Joined: Jan 2006
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From: Yooperville MI
I use Transtar 1221 - Hydroflex Super Hi-Build Waterborne Flexible Primer Surfacer on urethane bumpers. You can wet sand it and/or block it to remove defects or level the surface. It's water based and sprays right out of the can. The downside is, for small projects it only comes in 1 gallon cans, so you'll have some left over.
It's compatible with all manufactures top coats. I use PPG base/clear and if I plan to wet sand and polish the bumper afterwards I paint the bumper on the car (sitting in the holes but spaced away from the body)with no flex additives. This way you can wet sand and polish the paint. The downside is, if the bumper gets hit in the future, the paint could crack. If you plan on painting the bumper off the car and mount it later, you will need to use flex additive according to the spec sheets for the top coats you use but usually it's in the clear only. With flex additive, you can't wet sand and polish though.
If you use the Transtar, make sure to let it dry at least 24 hours before sanding to make sure it has bonded to the bumper.
It's compatible with all manufactures top coats. I use PPG base/clear and if I plan to wet sand and polish the bumper afterwards I paint the bumper on the car (sitting in the holes but spaced away from the body)with no flex additives. This way you can wet sand and polish the paint. The downside is, if the bumper gets hit in the future, the paint could crack. If you plan on painting the bumper off the car and mount it later, you will need to use flex additive according to the spec sheets for the top coats you use but usually it's in the clear only. With flex additive, you can't wet sand and polish though.
If you use the Transtar, make sure to let it dry at least 24 hours before sanding to make sure it has bonded to the bumper.
Thread Starter
Drifting
Joined: Jun 2005
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From: grand prairie texas
Originally Posted by ajstr1265
sherwin williams sells a high build flexible primer that eliminates the need to add flex to the primer. I do not like adding thing to the primer. I used this on the entire car and it works great.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
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From: Carmichael CA
Is the bumper still on the car? If so then you don't need the paint to flex. The bumpers were painted with the flexible agent so that they could be primed and installed on the car. The flexible agent will evaporate after a couple of days...at least that's what the paint shop told me when I replaced my bumpers and which I painted myself.
Thread Starter
Drifting
Joined: Jun 2005
Posts: 1,523
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From: grand prairie texas
the bumper cover is off of the car. It is fresh back from the soda blasters. Came out pretty good. I have a few small chips in the cover anybody know what best to fill them with?
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Le Mans Master
Joined: Apr 2005
Posts: 6,329
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From: Seattle Area WA
I've only used Sherwin Williams paint once on a Mustang I did for a gal. Very nice paint to work with, they have a very good reputation for their automotive paint, they just do not seem to be as popular as the PPG, Glasurit, Sikkens etc.
Drifting
Joined: Jan 2006
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From: Yooperville MI
Originally Posted by wnmech
the bumper cover is off of the car. It is fresh back from the soda blasters. Came out pretty good. I have a few small chips in the cover anybody know what best to fill them with?
Thread Starter
Drifting
Joined: Jun 2005
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From: grand prairie texas
Originally Posted by ahoover
As long as they aren't big craters, the Transtar mentioned earlier will fill them along with some block sanding. But don't sand it for at least 24 hours.
Drifting
Joined: Jan 2006
Posts: 1,944
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From: Yooperville MI
Originally Posted by wnmech
Is the transtar just for the flexable bumpers or can it be used as a primer for the whole car? I have been chemically stripping this car over the past few months and it is almost all down to bare glass.
I would use epoxy primer over your bare fiberglass. PPG DPLF is one of the best on the market but Transtar also has an epoxy primer that is half the cost. Epoxy primer over the entire body first, it will seal any loose strands and permanently glue them in place, then do your body work on top of the primer. Epoxy primer will stick to the fiberglass better than urethane and acrylic primers. Body fillers will adhere better to the epoxy primer than to fiberglass. DPLF has time constraints for top coating with fillers or sandable primers, where Transtar does not. So if you are a weekend warrior, DPLF will require pre-planning and be much more expensive to use. The product data sheets from the web sites can give you the details.
Burning Brakes
Joined: Mar 2006
Posts: 1,036
Likes: 2
From: Huntingburg Indiana
In general, flex additives are used in the coatings that are catalyzed. Flex additives work good, but will still crack if flexed too far. Also, not to start an argument here, but there is no reson to use an epoxy on bare fiberglass. It does not stick any better than any other primer. Paint adhesion is a mechanical bond. Paint sticks to the sanding scratches. If you are doing bodywork, there is no reason for putting it over epoxy. You have to rough up the surface for the filler. If you rough it up correctly you'll go through the primer, so you might as well do your work before priming. Good epoxy is not cheap. This is basically a waste. Epoxy is generally meant to be used as a wet on wet sealer. It really isn't meant to be sanded, but the ppg does sand pretty nice. If you have ever tried to sand cheaper epoxies, you know what I mean.
Last edited by bondoboy; Jul 7, 2006 at 10:18 PM.
Melting Slicks
Joined: Oct 1999
Posts: 2,581
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From: Tolar Texas
I'm not qualified to provide automotive paint advice. I'm a first time painter and this was the basic sequence that I followed:
After extensive sanding of my car with 400 grit, I shot a coat of PPG DPLF epoxy primer with the expectation of better overall adhesion and to seal in any oddball contaminants. I then layed two coats of PPG NCX 2k primer, wet-sanded w/400 grit, followed by another layer of NCX 2k primer, more wet-sanding w/600 grit, then topcoated with 3 coats of PPG CONCEPT DCC Acrylic Urethane single stage DCC9000 black followed by roughly 1 million hours of wet sanding with 1500/2000 grit
. I did not use any flex additive for my front and rear bumper covers which were painted seperately. I only got one small crack in a low profile area during re-assembly.
After extensive sanding of my car with 400 grit, I shot a coat of PPG DPLF epoxy primer with the expectation of better overall adhesion and to seal in any oddball contaminants. I then layed two coats of PPG NCX 2k primer, wet-sanded w/400 grit, followed by another layer of NCX 2k primer, more wet-sanding w/600 grit, then topcoated with 3 coats of PPG CONCEPT DCC Acrylic Urethane single stage DCC9000 black followed by roughly 1 million hours of wet sanding with 1500/2000 grit
. I did not use any flex additive for my front and rear bumper covers which were painted seperately. I only got one small crack in a low profile area during re-assembly.
Le Mans Master
Joined: Apr 2005
Posts: 6,329
Likes: 415
From: Seattle Area WA
I just wanted to add to Al's comments on the Transtar primer. Only the water based primer can sit forever before top coating, the solvent based Transtar stuff can not, it's like any other epoxy primer with time constraints.
Thread Starter
Drifting
Joined: Jun 2005
Posts: 1,523
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From: grand prairie texas
I was just viewing one of transtar's web site and they have a 1221 primer and a 1225 primer that both appear to be the same. What is the differance between the two? Also I noticed they are in black. If I paint my bumpers with the transtar black and should I primer the rest of my car black so that the final coat of Ontario Orange will match or will it not make a differance color mismatch of the primer. When I chemically stripped my car it appeared that the factory coat of primer under the factory Orange the primer was black
