Paint over base coat?

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PostPosted: Sun May 24, 2020 8:31 pm
NFT5 wrote:Yes. Because the water keeps the paper cleaner it cuts more. So P800 wet is roughly equivalent to P500 dry.


I rest my case.



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PostPosted: Sun May 24, 2020 8:42 pm
NFT5 wrote:No. P400 is too coarse to go under basecoat.

Sand the bar back with P180 then refine that to P400 on a DA. Apply primer and when the primer is dry, block that back with P800 wet or P500 dry before spraying metallic or pearl basecoat. If the colour is a solid you can use P600 wet for slightly faster levelling.


So youre saying shooting base over 500 grit is a good idea. Good luck with that.

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PostPosted: Sun May 24, 2020 8:44 pm
Masking completed and ready for primer.

2020-05-25 03.09.39.jpg
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PostPosted: Sun May 24, 2020 8:54 pm
Methyl Mike wrote:
NFT5 wrote:No. P400 is too coarse to go under basecoat.

Sand the bar back with P180 then refine that to P400 on a DA. Apply primer and when the primer is dry, block that back with P800 wet or P500 dry before spraying metallic or pearl basecoat. If the colour is a solid you can use P600 wet for slightly faster levelling.


So youre saying shooting base over 500 grit is a good idea. Good luck with that.


Apparently I'm not the only one

6000.jpg
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PostPosted: Sun May 24, 2020 10:54 pm
NFT5 wrote:Masking completed and ready for primer.

2020-05-25 03.09.39.jpg

Nice. I'm going to be doing something similar later on when I'm done with what I'm doing now.
So are you blending? I'm really learning about this stuff so forgive the questions. If you are blending? Im guessing yes.

Looks like you're only going to prime the areas that have been repaired am I correct

this is actually going to help a lot because I've been having questions about this. The panel is already painted and your repairing within the painted section. I really wanted to learn the steps to make it come out looking like it's all one piece and not showing that just that one piece was repaired.

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PostPosted: Sun May 24, 2020 11:24 pm
Righto. Continuing on....

Primer done. Normally I'd use a white primer but the one I have is a low build and I was a little concerned that I'd need more to take up any variances in the repair surface. So, I used the grey one. It is only necessary to prime over the repair area, not the whole panel. If the old paint is sound and properly prepared then there will be no adhesion issues. There is also the matter of cost and time needed to block out primer.

2020-05-25 09.54.38.jpg


Primer blocked out and I've marked what I used. P800 wet up to the body line and P1500 wet in the transition area above. From about halfway up that pillar just grey Scotchbrite. When doing jobs like this it's usually best to use the body shape to advantage and the change in angles to hide any differences in colour. As it turned out the colour match wasn't bad but this technique then makes it almost impossible to see the difference, especially since I had only a small area to blend and then use the area above the bodyline to take the overspray, again softening the change.

2020-05-25 11.03.52.jpg


Next is the application of basecoat in Value Shade 2, which is what is specified for the colour of this car. It looks a bit grey but it's actually off-white and without it I'd never have achieved coverage over the repair area. I could have used a white sealer or even an epoxy but base is quick and easy to make up and faster to dry.

2020-05-25 12.37.51.jpg


I can't stress enough how important it is to have the right colour substrate if you're doing repairs and want your repair to match. Because paints are not made for "full coverage" but rather to achieve an effect, having to lay many coats of base to cover primer is inefficient, costly and can impact on how well the repair will stand up over time.
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PostPosted: Mon May 25, 2020 2:07 am
NFT5 wrote:Righto. Continuing on....

Primer done. Normally I'd use a white primer but the one I have is a low build and I was a little concerned that I'd need more to take up any variances in the repair surface. So, I used the grey one. It is only necessary to prime over the repair area, not the whole panel. If the old paint is sound and properly prepared then there will be no adhesion issues. There is also the matter of cost and time needed to block out primer.

2020-05-25 09.54.38.jpg


Primer blocked out and I've marked what I used. P800 wet up to the body line and P1500 wet in the transition area above. From about halfway up that pillar just grey Scotchbrite. When doing jobs like this it's usually best to use the body shape to advantage and the change in angles to hide any differences in colour. As it turned out the colour match wasn't bad but this technique then makes it almost impossible to see the difference, especially since I had only a small area to blend and then use the area above the bodyline to take the overspray, again softening the change.

2020-05-25 11.03.52.jpg


Next is the application of basecoat in Value Shade 2, which is what is specified for the colour of this car. It looks a bit grey but it's actually off-white and without it I'd never have achieved coverage over the repair area. I could have used a white sealer or even an epoxy but base is quick and easy to make up and faster to dry.

2020-05-25 12.37.51.jpg


I can't stress enough how important it is to have the right colour substrate if you're doing repairs and want your repair to match. Because paints are not made for "full coverage" but rather to achieve an effect, having to lay many coats of base to cover primer is inefficient, costly and can impact on how well the repair will stand up over time.


Nice, just to make sure I understand correctly You sprayed your base pretty much over the primer and by the picture it looks like maybe a few inches past the primer. So your spraying the base on top of the existing base

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PostPosted: Mon May 25, 2020 2:14 am
From this point on the is no further sanding but it is important to tack after each coat.

Getting back to the original point of this thread, yes you can paint over existing paint, so long as it is sound and properly prepared. You can see that I've done that from the repair to the body line and a bit beyond.

Basecoat on and edges blended out

2020-05-25 12.56.47.jpg


Clear done

2020-05-25 13.08.43.jpg


Clearcoat blended in on bar. Yes, I know this is not what we normally recommend but in this case I had to do the two cars (his and hers) within a budget and that didn't allow for painting the full bar. I didn't blend on the body though - you can see that I cleared the cant rail all the way forward.

2020-05-25 13.17.14.jpg
Chris

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PostPosted: Mon May 25, 2020 2:25 am
Just some extras here.

Colour is a white metallic, standard 2 layer application.

Guns used.
- Iwata Air Gunsa AZ3 HTE2, 1.3mm. I love this thing for jobs like this. Great coverage and lovely, controllable blends. Not the ideal gun for basecoat on a full respray but unbeatable on repairs.
- Devilbiss GTi Pro Lite. 1.2mm with TE10 aircap. Perfect for matching that wetter European clear with just a hint of peel.

2020-05-25 13.30.15.jpg


2020-05-25 13.30.54.jpg


Cleaned up,put back together and ready to go. Job value $1250 and took me about 13 hours actual work time.

2020-05-25 16.24.06.jpg
Chris
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