What should primer look like after sanding?

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PostPosted: Tue Jan 11, 2022 5:18 am
Hi all, I'm a mechanic but very new to body and paint, trying out my skills on a spare wheel that had some damage.
I sanded it, filled in the missing metal with metal putty and have now sprayed on Septone primer filler (from a can, will be spraying everything from cans).
I'm in the process of sanding the primer with 400grit before base coat however, when I look really close at the surface, I can see some areas have a speckled appearance. When I run my finger over those areas, they only feel very faintly rough.
Should I sand more so the surface is visibly flat or will those rougher looking parts disappear when I put on the base coat?
I have uploaded two pics with the rough areas in about the center of each pic.
Attachments
Wheels2.jpg
Wheels1.jpg

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PostPosted: Tue Jan 11, 2022 9:50 am
And so you see why we don't care much for rattle cans here... I am assuming this is a 1k canned primer from the local auto parts store? Those cans sit on the shelves for weeks, months at a time and settle out. All your solids are sitting about a half inch deep or so over the "bubble like" bottom of the can. There are two balls in their that run around in the outer race of that can. If you are just dead set on using these things for some type of finishing do this..... pull a bucket or sink full of hot tap water, immerse the can about 2/3s of the way up and let set for about 15 minutes. Then take the can you are going to use out and grab it by the top and get a circular motion going on the can until you here those balls break loose down in that race. Continue spinning the can so they race around for about 3 minutes, then shake the can up and down hard for another 3 minutes or so. The little bits and pieces you have been seeing should have broken up and gone into solution by doing that. You will now also have about a 10 psi or so increase in can pressure which will allow more primer and higher solids to spray out.....
Final word of advice....ditch the rattle cans....for so many reasons I'm not even going to begin to get into that......
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PostPosted: Tue Jan 11, 2022 11:01 am
:goodpost:

Look at the sticky post on using Guide Coat.
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PostPosted: Tue Jan 11, 2022 12:45 pm
Dry spray
Sand more.
If using 1K products loose them!
Dennis B.
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PostPosted: Tue Jan 11, 2022 9:39 pm
Thanks for the info guys, I knew you wouldn't like the can idea but I wanted to try my hand at painting with those first before committing to buying an air compressor and guns etc.

I'll definitely try the warm water trick though!

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