Just went through a class recertifcation PPG class in April. New epoxy that's out is DPLV epoxy primers. They have a true 7 day Top coat window plus if you wanna sand them they sand a lot like a surfacer. I used the white DPLV 48 on some old gas station oil tanks I redid for a customer. He blasted them. I did some plastic work quick on them finished them in 220 quick on a DA. Threw two coats on them let them sit over the weekend. Monday am I DA'ed the ones that had some deeper sand scratches in the filler with 320 grit really quick. It didn't ball up on the paper like other epoxys do actually powdered like a surfacer. Wiped them off and put some industrial PPG AUE 200 white on them. They looked great. Now would I do a car this way no but the reps are saying they are seeing and pushing resto shops more on this line. Said its better where you can be direct to metal priming and if needed sand it. I was actually impressed. Just another option to think about as like they say you prime a car then reprime it if you don't get everything scuffed on the surfacers that have a day or less top coat or resand time window on them you end up with peeling paint.

As far as etch primers go. I vary on my use of them. Depends on the job. I like them cause if I use say dx 579 and don't get it all washed and dried off there is a film that I'm always bugged about. Where etch primers I dust them on and don't pool or run them I know I have a good chemical bond. Btw that's the easiest way i tell people about them. One is kinda like a glue( epoxy) the other has teeth that bight into the metal.