PROBLEM: White touchup paint get darker/yellowish while sanding.

V

Valinote

New member
I have a Performance White (code WT) colored 2004 Mercury Grand Marquis GS. This is the whitest, brightest, white color that Ford/Lincoln/Mercury makes. I had a large chip on the passenger side rear door, and multiple areas on the from and rear bumpers that needed attention. I found Dupli-Color NG FM 335 Scratch Fix to be almost perfect match color-wise; and i was going to follow that up with Dupli-Color NG SF 125 Clear Coat.



I prepped the areas by sanding with 600 grit Gator dri/wet sandpaper that had been soaked overnight in water. I also used a spray bottle of water with a few drop of Dawn dishwashing liquid to keep the sanding area lubricated..After drying the area I used denatured alcohol to remove any remaining wax or grease.



Appling the paint with a brush is kind of a challenge as the paint is rather thick and drys fast. Basically, (whether you're using the brush in the cap or a small artists brush), you get one clear stroke with the brush; If you try to do a second stroke over the same area while the paint is still wet you will get bristle marks and a rough gloppu finish. After waiting 24 houes,for the touchup to dky, I wetsanded the area with 600 grit paper until it was slightly below the surrounding base coat. Then I applied the clear coat, waited another 24 hourw, and finally wetsanded with Gator 1500 paper until it was flush with the surrounding area.



The problem is that as soon as I start to sand the touchup paint, it gets a little darker and/or yellowish and no longer matches the surrounding base coat. It seems that the more I have to sand, the worse it's gets. By the time I finish wetsanding the clear coat,, the touched up areas are all obviously darker and visibly notable. I've troed redoing some of the more obvious spots by removing all traces of the touchup paint with laquer thinner.and starting again from scratch. But the end results were the same.



I'm pretty frustrated at this point since I can't seem tp figure out what I'm doing wrong. Mechanically I've done a lot of shadetree wrenching, but I'm a newb when it comes to bodywork. Can someone please tell me what I'm doing wrong? Am I using the wrong kind of sandpaper? Is there a "special" sanpaper for lighter colored vehiclies? Please help me. I put a lot of time and effort into this trying to do a perfect job, and the results so far are very disappointing.



Thank you kindly in advance for any advice. Sincerely...



-Steve D





Thanks kindly in advance for any advice...8-)ONT=Courier New][/FONT]
 
valinote- I used different touchup paint on my Performance White Crown Vic, but I'll take a stab at this anyhow. I'd let the clear cure for a while before trying to wetsand it smooth. 24 hours wouldn't be nearly long enough for me, I'd rather wait a week or so (which is probably erring on the side of caution).



1500 works OK for leveling, but I'd sure follow up with something milder as 1500 scratches are a bear to compound/polish away.



One other thought, you could always try leveling it with Langka. No, it isn't "the proper, professional way to do it" compared to wetsanding, but on white it could quite possibly work fine. And there won't be all that sanding, which always makes me nervous when people report they're having any kind of issues. You don't have to wait quite as long for the paint to cure when using this kind of "solvent based" leveling approach, but I'd still give it more than 24 hours.
 
The discoloration isn't happening on the clear coat because I haven't applied it yet. It's occurring on the performance white basecoat and seems to get worse the more I wetsand. It would be a waste of time the way it looks now to apply the clear coat..I usually wait 24 hours after applying the basecoat before I do any wetsanding. Maybe it not long enough. I know you have to wait longer with the clear coat. If you don't think that 1500 grit is fine enough, what grits would you suggest for the final wetsand on the base coat, and then the clear coat before I apply polish and eventually wax?



Thanks for the pointer to the Langka system, that's an alternative I hadn't considered. I'll check it out.



I might just remove all the Duplicolor touchup paint with lacquer thinner, get some real paint in a can from a Mecury dealer, and shoot it with my airbrush. I've been working hard on this and the results so far have been disappointing. But I sinserely appreciate your advice.



Have a great weekend!



-Steve D
 
valinote- Thanks for the additonal info, that clarifies things for me.



What about not sanding the basecoat? Just apply the clear over top of it. I've had that work fine, the solvent action of the clear was sufficient without providing a good "tooth" via sanding. Eh, I hardly use any basecoat anyhow, at least not compared to the way I lay on the clear.



On white, you could even get by with what I used on my Perf. White Crown Vic, the DR Colorchips stuff. The paint part of that system is a single stage (no clearcoat). It didn't match my car 100%, but then white hardly *EVER* matches perfectly anyhow. It was good enough for that particular situation, maybe it'd work OK for you. It's leveling step is similar to the Langka, a solvent-based approach.
 
Nowadays the basecoats are so-oooo thin. It's easy to make a small chip into a large repair if you're not careful sanding. Don't ask me how I know that...8-]



The car came from Long Island where parking is at a premium I guess. It was garage kept and only has 22K on it. Body-wise it's perfect except for a chip on one passenger door and the front and rear plastic bumpers which look like they were rubbed up against and/or overflexed by another car parking. In the overflexed areas the paint is spiderwebbed, so any kind of brush touchup won't work for that. The rest is just some scratches and small chips. I think I'm going to give it a go with my airbrush. I mean it's just like painting an RC car except bigger. I just have to know how to thin the paint for the heat/humidity. Probably best to stop by a paint jobber here in Syracuse and let them fix me up with what I need. But one of my daughters is getting married this weekend and some AAU basketball trips with my son. So it will probably be a few weeks before I can get the supplies together and give it a try. I'll report back then. Kindest regards to all...



-Steve D
 
I suggest you pick up the little Harbor Frieght "detail gun" for around $10 rather than try it with an air brush. I got both, and for any area larger than an inch, need the regular type gun.

If you look at my photo gallery, the red Sears/Allstate I restored/painted, as well as the orange Buffalo were done with that cheap little detail gun rather than my larger, expensive HLVP or sipon guns.

Need 35 psi and about 2 to 3 cfm to make it work right. Suggest also that you pick up one of those cheap in line regulators and the cheap orange throw away water filter that goes in line when you use it.

Not a high dollar set up, won't break the bank and will do much better for you.

Grumpy
 
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