paint technology is really moving ahead quickly, like everything else- a few years back the tried & true undercoat system for bare metal was 2K self etching zinc primer (the green/yellow stuff, zinc base with acid reducer/activator), followed by 2K epoxy (paint and catalyst that hardens, that can be thinned 10% to make it flow like a sealer), followed by a primer surfacer to fill any sand scratches, then BC/CC or single state color
then urethane primers started being sold that could go right over bare metal, and also had somewhat good filling properties for bodywork/filler sandscratches, but had to be built up in 2-3 or more coats
now, they have polyester spray fillers that fill .010"-.012" sand scratches, and have the self etch built right into them- and use a hardener catalyst- this stuff sounds really amazing- you can sandblast an entire panel or car to bare metal, spray it with this stuff, it fills in all the imperfections- sand it, and put your base color or single stage paint right on the primer- done
.012" filling capability means, it will fill in 36/40 grit sandscratches- that means you can air board the seams on a quarter panel patch, then spray it with the poly, and then 220-400 it out and paint it- that saves a LOT of sanding time, and recoating
basically it's a one shot undercoat the etches, seals, and fills the surface- eliminating the need for self etch/epoxy/primer surfacer steps- it's "all in one"
one brand is actually called "ALL-YOU-NEED" and made by Claussen's- this stuff is pricey over $100/gallon w/activator- but I'm told it will fill in one pass, what other primer/surfacers take 3 passes to do
another brand is the well known Feather Fill brand, and it's called "Slick Sand"
Now I'm also hearing about DTM or "direct to metal" epoxy primers that are hybrids that build/fill more than old epoxies do- yet another product that will go from bare metal to paint and fill all in one shot
question- has anyone used these new high-build, high-tech all-in-one polyester primers, if so how did they work out ?