Primer, does this look correct?

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PostPosted: Tue Jun 04, 2019 4:44 pm
I'm not a big fan of overthick primer so put a lot of effort into getting the substrate right. Usually just two medium wet coats so that there is a minimum amount of sanding and drying time necessary. Ultimately this saves time which, for me, is money. A car sitting in the booth, drying, is just taking up space so I use fast curing primers or 1K which I can sand and topcoat in 15-20 minutes. Can't have it too thick or it will take too long. The 2K primers I use are primer/surfacers so go on very smooth and cure in 45 minutes which is still ok.
Chris



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PostPosted: Wed Jun 05, 2019 1:47 am
Saving time is a concept i have not experienced lately. I think this is the fifth time i prime the bumper due to diffrent problems. Worst part is that i finished the bumper last year with great result but a while back a cat had a party in my storage room resulting in a destoryed bumper.

Anyhow, i sanded the peel and overthick primer with p500 without much problem. Going to do p600/800 then i might get som paint on this thing :goodjob:



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PostPosted: Sun Jun 09, 2019 2:43 pm
First of all i would like to thank NFT5 and all the others who helped me out with my primer problems.

So i moved away from the crappy mipa grundfiller and started using mipa 2k acrylic filler, what a difference! All my previous primer problems whent away except that i sprayed it so i still had a lot of peel but with your guys help and some practices in speed and overlap i got it super smooth.

The only problem is that i still get scratches showing trough my basecoat and i can't understand if p800 is to corse or if my sanding technique is the problem.

So here is the newly painted front fender and what i done to it:

Sanded old finish down, p240-400.

Then mipa grundfiller sanded with p500, 3 coats of mipa 2k acrylic filler, had some peel but tought it would be ok so sanded with 500-600 dry then p800 wet. Had small burn troughs in two corners so I then put one more wet coat of 2k acrylic filler, result which show in pics.

Since it was very smooth i just sanded it with p800 wet, which shown i pic 2. I did some more sanding after pic was taken. No guide coat left.

Painted with standox standohyd plus, waterborne basecoat. I spray 1 dust coat just to make sure nothing werid was going to happen then 1 full + 1 effect directly after like datasheet said. When wet no scratches showing. When dry some random scratches showing which i tought clear would cover, 1 light coat and 3 wet coats of profix cp25 clear, it did not cover. See pics.

The fender looks very good but i have random scratches here and there.

The datasheet for primer say p600 dry or p800 wet. Datasheet for base say p800-1000. I used 3m p800 wet and dry papers with small durablock most of the time, only used longblock in the middle sading in X motion most of the time or following the shape of the fender.

To me this looks like p800 scratches showing, i dont think its comming from under the primer.
I know i can cover by putting on 3-4 coats of base but thats just wrong.

Next up im planing on using p800 wet then p1000 wet but whats the problem here? Why do you guys think i got sanding marks showing?
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