What's the difference?

[Hedgehog]

Hi I'd like to know what's the difference between sandable primer and filler primer? Which is better for what job? Thank you

[Ace-Garageguy]

In my humble experience, they're both "sandable"..........(as opposed to some enamel primers and primer-sealers which need to be left unsanded to insure an unbroken surface film which will impede penetration of the solvents from subsequent coats).

"Filler primer" is generally thought of as "high-build-primer", and often labeled as such. A thin coat will dramatically highlight flaws in raw bodywork you might have trouble seeing otherwise. It builds quick with successive coats, covers fast, and fills small irregularities, course sanding scratches, etc. in bodywork. In high humidity or when using multiple coats, it can take a few days to shrink in fully, and to be ready to sand. I will usually prime bodywork with Duplicolor Gray Filler Primer, allow it to fully dry, then sand the worked area and primer again, and repeat as necessary until I have the surface finished to my satisfaction, sanded up to 400 or 600 grit wet. Because it is high-build, it will also tend to obliterate details if used excessively.

"Sandable primer" is just that....it can be sanded to remove very minor imperfections, slight orange peel, or dust nibs. It is NOT a high-build product and is intended to fill maybe 400 grit sanding scratches in your work, to provide a tooth or adhesion coat for paint, or to change the color of the substrate and so effect the final color. I often use Duplicolor Sandable White Primer as the last coat of primer under translucent colors, like the lighter Testors one-coat metallic lacquers (gold, orange, etc). It does a nice job of brightening the color, and fills the 400 or 600 grit scratches left from the final sanding of the Filler Primer. I usually final-sand the sandable primer with 1000 to 1500 grit wet, again, to remove any slight orange peel or dust nibs, prior to shooting color.

Edited July 23, 2012 by Ace-Garageguy

[Hedgehog]

So first you use filler primer and then sandable primer in the same proyect?

[Ace-Garageguy]

So first you use filler primer and then sandable primer in the same proyect?

I do, because I usually do heavy mods and a lot of bodywork. If you're just sanding mold lines off of an otherwise good body (with 400 or 600 wet), then sandable primer is all you need. It simply depends on the degree of filling you want the primer to do.

Edited July 23, 2012 by Ace-Garageguy

[Hedgehog]

Oh ok thank you for such a help