Chip Repair Problem

[AustrianOak82]

I am doing a chip repair today and for whatever reason the repaired spots are turning dark or black after wet sanding. What is going on here?

I wet sanded the blobs with 2000, then 2500. I ended up with this.

 

[mwoolfso]

Single stage?

 

[AustrianOak82]

No, maybe even 3 stage. Toyota 4runner. The only ting I can think of is that they didn't mix clear in with the paint and when I wet sanded it just blended it all together into black. But I am baffled.

 

[7PaintGuns]

Was it nice and red before you sanded it? You may be laying down the flake or you need some kind of colored sealer before application.

 

[GSKR]

I am doing a chip repair today and for whatever reason the repaired spots are turning dark or black after wet sanding. What is going on here?

I wet sanded the blobs with 2000, then 2500. I ended up with this.

Can be 2 promblems ,touch up not matching or blending in.even if you got the paint from the dealer that's a hard color to do a touch up .did you shake the bottle before applying color.sometimes there is to much metallic or flake bunched up on the brush itself.silver is hard as well you have to go with a lighter silver than what's on the car.

 

[AustrianOak82]

The paint matched near perfect after application. I dried it with a heat gun for 3-4 minutes and let it sit another 10 minutes with a fan on it. It was dried and not tacky when I started sanding and was a near perfect match. One I started sanding, it turned dark gray.

 

[irvsmith]

Heat related?

 

[7PaintGuns]

I've seen this before but I'm not sure what causes it. I was told its because the metal flake is laying down after sanding. Only solution I have found is to TU the chip and follow with clear coat for sanding and leveling.

 

[TRDTACO]

What color is the sandpaper you are using?

 

[Setec Astronomy]

Sounds like whatever force-drying you did caused, as others have noted, the metal flake to sink/float to all the same "depth", so when you sand down to that level it's all flake and no paint.

 

[AustrianOak82]

Heat related?

I don't think so. I have dried chips quite a few times. I usually stay about a foot away and I check the surface temp every 30 seconds or so.

I've seen this before but I'm not sure what causes it. I was told its because the metal flake is laying down after sanding. Only solution I have found is to TU the chip and follow with clear coat for sanding and leveling.

TU?

What color is the sandpaper you are using?

It's gray. Meguiar's Unigrit.

Sounds like whatever force-drying you did caused, as others have noted, the metal flake to sink/float to all the same "depth", so when you sand down to that level it's all flake and no paint.

The only thing I would say there, is when the paint was dry (just before sanding) it was a near perfect match. Very frustrating. Luckily it's a friends car. If there was no clear mixed in, would it result in what you mentioned as well?

 

[Setec Astronomy]

The only ting I can think of is that they didn't mix clear in with the paint and when I wet sanded it just blended it all together into black.

If there was no clear mixed in, would it result in what you mentioned as well?

I'm not sure I understand--I don't think touchup paint has any relation to actual basecoat or clearcoat, it's a separate animal. There would be no reason to mix clear paint into touchup paint.

Clearcoat is 2K which means it's a two-part catalyzed paint. Some basecoats are also catalyzed urethanes, but in any event the touchup paint you get is not the same type of paint that you would use as either basecoat or clearcoat, at least that's the way I understand it.

TU?

I believe he was abbreviating "touchup" and suggesting that you put down your color, then apply clear over it before sanding, so you will be sanding clear and won't have to worry about any flake orientation issues.

 

[AustrianOak82]

I got the paint from O'Reilly Auto Parts. They mixed it there, on site and I got a pill bottle sized amount. Since they mixed it on their own, I figured they needed to mix clear with it and possibly forgot, leading to my problems. But, if there is clear in there, then I would end up in the same spot. If the paint is not smooth and I apply clear over the top of it with the intent on sanding just the clear, then I am not smoothing the base coat itself.

 

[Setec Astronomy]

I got the paint from O'Reilly Auto Parts. They mixed it there, on site and I got a pill bottle sized amount. Since they mixed it on their own, I figured they needed to mix clear with it and possibly forgot, leading to my problems.

Once again, as I understand it, when you get a bottle of touchup paint, whether pre-mixed or custom-mixed as you purchased, they are not taking basecoat paint and mixing clear into it, they are mixing single-stage paint to the appropriate color to match the original basecoat/clearcoat finish.

As I noted before, basecoat is basecoat, clearcoat is clearcoat, and touchup paint is different, it's single-stage paint. Basecoat is not the same as single-stage paint. Unless I'm mistaken. We have some painters on the forum, hopefully one of them will chime in.

 

[AustrianOak82]

I wanted to bump this thread and see if anyone had any additional input on this issue. I am getting the car back for round two in about a week and wanted to see if I could fix it.

From what I gather from everyone, drying with the heat gun possibly caused the flakes to settle/float and in turn became black upon sanding since I would only be sanding the flakes. This still doesn't make sense to me though, since the paint was a near perfect match before I started sanding. You would think the paint would be the same color pre and post sanding ? I think I will try this approach next time:

1. Apply paint as needed.
2. Allow to air dry for at least two hours until it's not tacky.
3. Wet sand with 2500, then 3000.
4. Compound or polish as needed.

*Setec, sorry for the confusion. I think I missed reading one of your earlier posts and my reply didn't make sense. I follow you now.