Hi all. A question for the paint experts in this group. I will also post this in the Paint/Body section, even though that doesn’t get as much traffic.

The problem is in an attempt to repair a chip in my fender. Car is painted with PPG Cortez Silver basecoat and DCU 2002 clear. I have all the original paint so color and compatibility are not a problem.

The chip is about 3/8” in diameter and I have filled it with basecoat somewhere up to the level of the original clear.

I sanded the area with minimal overlap onto the clear as shown in this picture. The tape is model airplane tape so it is pretty thin. The sandpaper is a bit thicker. With the sanding stick shown I roughed down to a spot just under the original clear and then airbrushed a spot of color on top of that.




At that point I had a nice spot of color, with maybe some overspray and a scratched up halo from the 600 grit sandpaper dot. I figured at that point airbrushing some clear would fill in the scratches in the original clear and I should get a solid clear surround. I DIDN’T and I don’t know why. Here’s what I got:




The sanded original clear and the spray on top of it came out darker. This looks pretty bad considering I have all good materials. Here is a diagram of the process I followed.




My problem is the halo (i.e. the question mark in the cross section picture), I really don’t understand why it is there. I didn’t sand down to the original basecoat. What should be there is old sanded clearcoat and new airbrushed clear coat and that’s all. So why is it darker? Could it possibly be 600 grit sandpaper residue? Or the new clear didn’t really fill the sanded scratches and I have a foamy area?

One possibility is to try to cover this with some aftermarket repair clear tinted a bit with silver.


Why that? Well the DCU clear can’t be tinted, but the aftermarket can so that may cover up the halo. That stuff wipes off pretty easily with lacquer thinner so I may try that and see what happens.

Your expertise or analysis or suggestions are most welcome

 

Pretty sure if you are spraying clear you need blending clear or solvent/ reduction to melt into the original clear.
i would also go to 800-1200..
blend then color sand over repair and buff.
Do not spray color over the original clear

 

ignatz

I agree with interpon that you went too coarse on the sandpaper grit. I had great success blending clearcoat into the lacquer in the spoiler area using 1200 grit.
I also used a product called Fade-out. U-Pol
A good paint shop will have it. One quick pass is all it takes to blend. It sort of melts the clear into the paint so you don't have an edge. (That tape will leave an edge.)
One light spray about five minutes after the clear application. Too much and it will run!
Hope this is helpful.

VS

 

I sprayed just a dot over the sanded surface with the air brush to just cover the chipped area with color. That came out nice and smooth and no visible edge so I figured I was good with the clear. Per the instruction on the can I thinned it, added hardener, and sprayed a larger area over the color with clear. As you say, that was probably too thick to completely fill in the remaining 600 grit area. Sounds like my remedy is finer paper and a thinner initial coat.
The tape in the picture was just an area guide for the dot of sandpaper I used. I've learned my lesson trying to mask or soften the edge with tape, it's never quite worked out. The tape comes off before the air brush gets used. The air brush is the best solution to a soft enough edge. The tape's role was to let the sandpaper cut into the area a bit so I could get a depression to be filled with color. That actually seemed to work out OK. See my comment to interpon.

About the Fade-out and grit, I'll have to work that a bit. Paint shops for us amateurs have dried up around here. I don't even know if I can get finer grit sandpaper, 600# was all I had. Mail order may be my only way out, perhaps Eastwood or the place I got the chip repair bottles. Fade-out may not work with DCU in which case I will try a very thin light coat of clear over a better prepped area.

I had decided the aftermarket was a last resort as I had the right materials on hand. I got those bottles but haven't used them. The color match seems perfect and the clear they sent seems like it would flow pretty nicely, but it doesn't come with a hardener so I was reluctant. Maybe I will try it on a less visible chip if that happens.

Thanks interpon and VS, I'll try a do over, hopefully making this repair less visible. The halo just jumps out over my otherwise near perfect paint job and I will see it everytime I get in the car.

This all seems a little wordy for what it is so thanks for bearing with me!