[HTFreak]

How do I "level" and "smooth" out the final and last layer (out of three levels)
of primer that I rolled on (with Cigar Foam rollers) to a MDF component rack that I built?

I used "bondo" from home depot to fill in cracks between the MDF joints in a lot of places. Should I just use Bondo to also fill in some uneven blemishes and defects in the Primed MDF before I paint it OR is there a better solution? I am sanding the last layer of primer with 220 grit sand paper using the orbital sander.

Thanks! :smile:

 

[Gymschu]

Crackshot is much easier to sand than Bondo.

 

[afrig]

Bondo seems like overkill. When priming you should sand as you go. Lay a coat, let it dry, sand rough spots, wipe down (If I'm not using a dry rag I'm using isopropyl alchohol because it evaporates quickly), and prime again. Then sand the rough spots and paint. I don't think I've ever used more than two good coats of primer. Not even on the ship's steel during my time in the Navy. I guess it would depend on the primer you're using.

Whenever I am smoothing out the surface that I will paint over I don't use any tools like an orbital. I find hand sanding it gives me a smooth surface and takes away much less paint of primer.

 

[Jmayspaint]

Crackshot like suggested above can work. Or if you want something harder, I really like Bondo spotting putty for detailing out shallow imperfections.

It's similar to Bondo, but only one part so there's no mixing. It knifes down well, dries fast, and sands easily. The drawback is that it's red, and generally requires re priming. I like to use spray can primer to hit the patched spots before painting if there's not too many of them.

I believe 3M makes a version of this that's light grey, but I haven't tried it.


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[ToolSeeker]

Sounds like maybe you were trying to fill the voids with primer, 3 coats. Primer will not fill defects. A pic of what you have may help.