Is it possible to make undetectable spot repairs?

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PostPosted: Wed Jul 06, 2022 1:59 pm
Hi everyone,

I'm working on wrapping up the paint job on my antique vehicle (Old English White). This year it's the front end.

Thought I had it perfect the first time but ended up with a LOT of trash in the base and clear that forced me sand it down and respray.

Second time was much better but ended up with about a dozen more small pieces of trash. I burned through the clear and base on several. The others I couldn't get out but stopped before burning through. I sanded with 600, touched them all with a small airbrush, sanded with 2000 and then sprayed clear. I also sprayed the edges lightly with reducer to blend them.

The clear overall looks amazing, even without any block sanding. But six of my touchups can be seen with a flashlight held at an angle (they look ok from overhead). Four have slight shadows and two have an ever so slightly different color.

I don't have enough base to respray at this point. I'm wondering if I should chase these last four down with the same procedure? Or just move on and finish the vehicle?

I will post photos once the clear dries.



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PostPosted: Wed Jul 06, 2022 10:15 pm
yep lets see some pictures. did you blend the touchup spots properly?
Jay D.
they say my name is Jay

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PostPosted: Thu Jul 07, 2022 9:35 am
You should never sand base coat, if you have to, to remove trash, basecoat has to be resprayed with another coat of base before clearing.
Every tech sheet I've read warns against sanding base.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Thu Jul 07, 2022 9:36 am
Regarding blending, I used the same base color I had sprayed a couple of days earlier so it was an exact match. It did have some texture to it that gave it a gloss, so I went over it with 2000 and that seemed to help.

Some good news though. The shadows came out with block sanding. This was really unexpected as it was clear that they were coming from where I had applied some spot touches of basecoat. It's almost as if some of the base had clouded up and floated into the clear. They came out with 600 and are nearly undetectable now (you have to be within 6").

I took out some more trash and ended up with three very small spots where I partially went through the base and thinned it out. I'm going to hit them with an airbrush (base then clear) and call it a day.



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PostPosted: Thu Jul 07, 2022 9:39 am
JCCLARK wrote:You should never sand base coat, if you have to, to remove trash, basecoat has to be resprayed with another coat of base before clearing.
Every tech sheet I've read warns against sanding base.


I was wondering about this. I recently saw a video in which they lightly sanded a spot in the base coat and sprayed. But then I checked the TDS and it says the same thing you do (ie: don't sand).

I tried it without the 2000 the first time and it was very detectable... I had to respray the entire body after.



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PostPosted: Thu Jul 07, 2022 10:00 am
Here's a photo of the panel with about 10 spot repairs or so (block sanded with 600, not shiny yet):

Image


And here is a photo of two remaining spot fixes, just after spraying. As you can see, the base sticks out like a sore thumb. I guess I could try not sanding them and spraying clear directly over... it could just be the gloss that makes it stand out.

Image



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PostPosted: Thu Jul 07, 2022 10:48 am
you shouldn't sand the base. white is difficult because if you touch it with anything like sandpaper, its going to make it dirty and you're going to see it under your clear. it very difficult to get it clean. sanding will also change the tone of the color some.
Jay D.
they say my name is Jay



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PostPosted: Thu Jul 07, 2022 1:06 pm
Ok, I'll give it a shot.



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PostPosted: Thu Jul 07, 2022 8:09 pm
Well, you guys were right. The touchups looked really bad before clearcoat, but completely undetectable after the clear went on!



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PostPosted: Fri Jul 08, 2022 3:16 pm
So I buffed it out today and I'm 97% happy. The other 3% is due to three of my spot repairs which showed through the final job.

The good news is that dozens of spot repairs are absolutely undetectable (as seen in the photos below). However, those last three buggers appear to be tiny dents in the surface, where I must have attacked the spots too aggressively with sandpaper. They look a lot like minor rock dents. I estimated their depth using a paint thickness meter to be about 30-40 microns. I couldn't even get a photo of them but you can clearly see them at the right angle.

So I'm thinking I will sand them out and apply another 2-3 coats of clear. I would rather just try to sand it flat but unfortunately, the base needs a slight touchup in one of them.

Think that will do the trick?

Image


Image
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